Log Message:
Update databases/elasticsearch to 2.4.0.

=== Breaking changes

Network::
- Single comma-delimited response header for multiple values

=== Deprecations

Geo::
- Deprecate optimize_bbox on geodistance queries
- Deprecate geohash parameters for geo_point parser

Mapping::
- Add deprecation logging for '_timestamp' and '_ttl'.

Query DSL::
- Deprecate soon-to-be-unsupported queries.

REST::
- Deprecate camelCase usages

Search::
- Deprecate sort option reverse.

Settings::
- Deprecate bootstrap.mlockall
- Deprecate camelCase settings magic

Snapshot/Restore::
- Adds deprecation notices on removed BlobContainer methods

=== New features

Geo::
- Add CONTAINS relation to geo_shape query

Plugin Cloud AWS::
- Add support for path_style_access

Reindex API::
- Backport: Reindex's throttling

=== Enhancements

Circuit Breakers::
- Limit request size

Cluster::
- Batch process node left and node failure 2.x

Core::
- Improve performance of applyDeletedShards
- Sliced lock contention 2.x
- Kill thread local leak
- Remove hostname from NetworkAddress.format (2.x)

Dates::
- Improve TimeUnitRounding for edge cases and DST transitions

Internal::
- Turn RestChannel into an interface
- Require executor name when calling scheduleWithFixedDelay
- Implement available for all StreamInput classes

Java API::
- Add created flag to IndexingOperationListener#postIndex

Logging::
- Add shardId and node name in search slow log

Mapping::
- Mappings: Allow to force dots in field names

Network::
- Exclude admin / diagnostic requests from HTTP request limiting
- Netty request/response tracer should wait for send
- Exclude specific transport actions from request size limit check
- Provide better error message when an incompatible node connects
  to a node

Packaging::
- Increase default max open files to 65536
- Allow configuring Windows service name, description and user

Parent/Child::
- Allow adding additional child types that point to an existing
  parent type

Query DSL::
- Fixed QueryParsingException in multi match query

REST::
- CORS handling triggered whether User-Agent is a browser or not

Reindex API::
- Switch default batch size for reindex to 1000

Scripting::
-  Mustache: Add util functions to render JSON and join array
   values
- Compile each Groovy script in its own classloader

=== Bug fixes

Aggregations::
- Fix potential AssertionError with include/exclude on terms
  aggregations.
- Pass resolved extended bounds to unmapped histogram aggregator
- Fix "key_as_string" for date histogram and
  epoch_millis/epoch_second format with time zone
- Fix TimeUnitRounding for hour, minute and second units
- Adds serialisation of sigma to extended_stats_bucket pipeline
  aggregation
- ExtendedStatsAggregator should also pass sigma to emtpy aggs.
- Prevents exception being raised when ordering by an aggregation
  which wasn't collected
- Setting 'other' bucket on empty aggregation

Allocation::
- Rebalancing policy shouldn't prevent hard allocation decisions

Analysis::
- Add 'Character.MODIFIER_SYMBOL' to the list of symbol
  categories.

Bulk::
- Copy headers and context to individual requests inside a bulk

CAT API::
- Fix merge stats rendering in RestIndicesAction
- Expand wildcards to closed indices in '/_cat/indices'
- Fix column aliases in '_cat/indices', '_cat/nodes' and
  '_cat/shards' APIs

CRUD::
- Prevent TransportReplicationAction to route request based on
  stale local routing table

Cluster::
- Fix block checks when no indices are specified
- Cluster stats: fix memory available that is always set to 0

Core::
- Throw exception if using a closed transport client
- Fix misplaced cast when parsing seconds
- Don't try to compute completion stats on a reader after we
  already closed it

Dates::
- Make sure TimeIntervalRounding is monotonic for increasing dates
- Fix invalid rounding value for TimeIntervalRounding close to DST
  transitions
- Fix problem with TimeIntervalRounding on DST end

Highlighting::
- Plain highlighter should ignore parent/child queries
- Let fast vector highlighter also extract terms from the nested
  query's inner query.
- Skip all geo point queries in plain highlighter
- Exclude all but string fields from highlighting if wildcards are
  used

Indexed Scripts/Templates::
- Don't ignore custom sharding settings in create index request
  for '.scripts' index

Internal::
- Fix filtering of node ids for TransportNodesAction

Logging::
- Add missing index name to search slow log.

Mapping::
- Mapping updates on objects should propagate 'include_an_all'.
- Mappings: Fix detection of metadata fields in documents
- Fix not_analyzed string fields to error when
  position_increment_gap is set
- Automatically created indices should honor
  'index.mapper.dynamic'.
- Process dynamic templates in order.
- Fix cross type mapping updates for 'boolean' fields.
- Fail if an object is added after a field with the same name.

Packaging::
- RESTART_ON_UPGRADE incorrectly named ES_RESTART_ON_UPGRADE in
  sysconfig

Percolator::
- Set the SC and QPC type always to '.percolator' in percolate api
- Fixed NPE when percolator filter option is "empty".

Plugin Analysis Kuromoji::
- Prebuild Japanese Stop Words Token Filter

Plugin Cloud AWS::
- Support specific key/secret for EC2
- Add missing permission for S3 repository

Plugin Cloud Azure::
-  Make discovery-azure work again on 2.4 branch
- Fix remove of azure files

Plugin Cloud GCE::
- Fix NPE when GCE region is empty

Query DSL::
- Make parsing of bool queries stricter
- Fix NullPointerException in SimpleQueryParser when analyzing
  text produces a null query
- Apply the default operator on analyzed wildcard in
  simple_query_string builder
- Apply the default operator on analyzed wildcard in query_string
  builder

REST::
- Do not decode path when sending error
- CORS should permit same origin requests
- Allow CORS requests to work with HTTP compression enabled
- Fixes reading of CORS pre-flight headers and methods
- Fix OOM in AbstractXContentParser

Recovery::
- Backports Notify GatewayRecoveryListener on failure

Reindex API::
- Make reindex and lang-javascript compatible

Search::
- AllTermQuery must implement equals/hashCode.
- Add ref-counting to SearchContext to prevent accessing already
  closed readers
- Fix '_only_nodes' preferences
- Speed up named queries.

Snapshot/Restore::
- Handle 'indices=["_all"]' when restoring a snapshot
- On restore, selecting concrete indices can select wrong index

Stats::
- Fix sync flush total shards statistics

Translog::
- Translog can delete valid .ckp file when views are closed after
  the translog
- Call ensureOpen on Translog#newView() to prevent
  IllegalStateException

=== Upgrades

Core::
- Update jackson to version 2.8.1 (on 2.4 branch)
- Upgrade lucene to 5.5.2

Dates::
- Upgrade joda-time to 2.9.4

Internal::
- Update Jackson 2.6.2 -> 2.6.6 (latest and final 2.6 patch)

Network::
- Upgrade to netty 3.10.6.Final

Plugin Cloud AWS::
- Update aws sdk to 1.10.69 and add throttle_retries repository
  setting