Log Message:
Update databases/couchdb to 2.1.1.

couchdb 2.1.1
- CouchDB now supports compilation and running under Erlang/OTP 20.x
- The couch_peruser functionality is now really fixed
- The cookie domain for AuthSession cookies, used in a proxy
  authentication configuration, can now be customized via the ini file
- It is now possible to modify shard maps for system databases
- Due to an Erlang bug (ERL-343), invalid paths can be returned if
  volumes are mounted containing whitespace in their name (fixed)
- The current node's local interface can now be accessed at
  /_node/_local/{endpoint} as well as at
  /_node/<nodename>@<hostname>/{endpoint}.- The Dockerfile in the source
  repository has been retired
- Fauxton now uses a version of React with a BSD license.
- CouchDB now no longer decompresses documents just to determine their
  uncompressed size
- The design document cache (ddoc_cache) has been rewritten to improve
  performance
- Mango now supports partial indexes
- Mango queries can now be paginated
- Mango _find accepts an execution_stats parameter
- Mango now requires that all of the fields in a candidate index must
  exist in a query's selector
- Other minor improvements.

couchdb 2.1.0
- The Mango _find endpoint supports a new combination operator,
  $allMatch.
- New scheduling replicator.
- Other minor improvements.

See changelog for the 2.1.x branch for more:

  http://docs.couchdb.org/en/latest/whatsnew/2.1.html