Log Message:
Update couchdb to 1.6.0.

- COUCHDB-2200: support Erlang/OTP 17.0 #35e16032
- Fauxton: many improvements in our experimental new user interface,
  including switching the code editor from CodeMirror to Ace as well
  as better support for various browsers.
- Add the max_count option (UUIDs Configuration) to allow rate-limiting
  the amount of UUIDs that can be requested from the /_uuids handler
  in a single request (CVE 2014-2668).
- COUCHDB-1986: increase socket buffer size to improve replication speed
  for large documents and attachments, and fix tests on BSD-like systems.
- COUCHDB-1953: improve performance of multipart/related requests.
- COUCHDB-2221: verify that authentication-related configuration settings
  are well-formed.
- COUCHDB-1922: fix CORS exposed headers.
- Rename proxy_authentification_handler to proxy_authentication_handler.
- COUCHDB-1795: ensure the startup script clears the pid file on termination.
- COUCHDB-1962: replication can now be performed without having write access
  to the source database, the replication checkpoint interval is now
  configurable.
- COUCHDB-2025: add support for SOCKS5 proxies for replication.
- COUCHDB-1930: redirect to the correct page after submitting a new document
  with a different ID than the one suggested by Futon.
- COUCHDB-1923: add support for attachments and att_encoding_info options
  (formerly only available on the documents API) to the view API.
- COUCHDB-1647: for failed replications originating from a document
  in the _replicator database, store the failure reason in the document.
- A number of improvements for the documentation.