MB-10171: added capturing of master vbucket _local docs to /diag

Particularly so that we can see xdcr checkpoints.

Change-Id: I658852aa3587541527684049529f4e0c9ee35447
Reviewed-on: http://review.couchbase.org/34028
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
MB-100 lower the log level for bunch of messages from info to debug

Change-Id: Id34d54b55abee09135ae00983c72bc35c6879048
Reviewed-on: http://review.couchbase.org/34349
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
MB-9980: documented graceful failover REST API

Change-Id: Iaf26cb5d8452cb8f4de336f0dae711466fcd22f6
Reviewed-on: http://review.couchbase.org/34393
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Merge commit '73039da8db97...' into master

* commit '73039da8db977bd6317558cf7027d0993ffe19c8':
  MB-10171: added capturing of master vbucket _local docs to /diag

Conflicts:
	src/diag_handler.erl

Change-Id: I4def5b284977f8b211b6c44588778d09853f48c5
Merge "Merge commit '73039da8db97...' into master"