Bump fauxton, docs, version to 2.3.0

The configuration of query servers is done via environment variables.
Calling os:getenv every time we need a new query process is expensive.
Instead we extact all configured query servers from the environemt on
`couch_proc_manager` startup and cache them in ets table.

fixes #1772

Previously the compaction daemon looked for design docs in each shard file.
This worked well for versions < 2.x, however, for clustered databases design
documents will only be found in their respective shards based on the document
id hashing algorithm. This meant that in a default setup of Q=8 only the views
of one shard range, where the _design document lives, would be compacted.

The fix for this issue is to use fabric to retrive all the design documents for
clustered database.

Issue #1579

Check code format before running elixir test suite