Log Message:
Update ruby-sequel to 4.49.0

=== 4.49.0 (2017-08-01)

* Make dataset_associations plugin automatically alias tables when using
  many_through_many associations that join the same table multiple times
  (jeremyevans)

* Deprecate using a :pool_class Database that is not a class or a symbol for a
  supported pool class (jeremyevans)

* Deprecate :eager_loading_predicate_key association option and association
  reflection method (jeremyevans)

* Deprecate Model.serialized_columns in the serialization plugin (jeremyevans)

* Deprecate Model.cti_columns in the class_table_inheritance plugin
  (jeremyevans)

* Deprecate SQL::AliasedExpression#aliaz, use #alias instead (jeremyevans)

* Deprecate SQL::Function#f, use #name instead (jeremyevans)

* Deprecate treating cross join with conditions as inner join on MySQL
  (jeremyevans)

* Deprecate ConnectionPool#created_count, use #size instead (jeremyevans)

* Deprecate ConnectionPool::CONNECTION_POOL_MAP, use the :pool_class option to
  specify a non-default connection pool (jeremyevans)

* Deprecate Sequel::IBMDB::Connection#prepared_statements= in the ibmdb
  adapter (jeremyevans)

* Deprecate DEFAULT_OPTIONS in validation_helpers, override
  default_validation_helpers_options private method instead (jeremyevans)

* Deprecate model association before callbacks returning false to cancel the
  action (jeremyevans)

* Support native offset syntax on Oracle 12 (timon) (#1397)

* Deprecate Dataset#nullify! in the null_dataset extension (jeremyevans)

* Deprecate Dataset#autoid=, #_fetch=, and #numrows= in the mock adapter
  (jeremyevans)

* Deprecate loading plugins by requiring sequel_#{plugin} (jeremyevans)

* Add Model.sti_class_from_sti_key in the single_table_inheritance plugin to
  get the appropriate class to use (Aryk) (#1396)

* Make Sequel::Error#cause use #wrapped_exception if it exists on ruby 2.1+
  (jeremyevans)

* Make Dataset#where_all, #where_each, #where_single_value core dataset
  methods instead of just model dataset methods (jeremyevans)

* Make Database#extend_datasets and Dataset#with_extend now use a
  Dataset::DatasetModule instance if given a block (jeremyevans)

* Add Sequel::Dataset::DatasetModule, now a superclass of
  Sequel::Model::DatasetModule (jeremyevans)

* Make composition plugin with :mapping option work correctly if
  Model#get_column_value is overridden (jeremyevans)

* Support Dataset#paged_each :stream => false option on mysql2 to disable
  streaming (Aryk) (#1395)

* Make datetimeoffset handling in the jdbc/sqlserver adapter work on more
  drivers (jeremyevans)

* Make alter_table add_primary_key work correctly on H2 1.4+ (jeremyevans)

* Support :sslrootcert Database option in the postgres adapter (dleavitt)
  (#1391)