MB-1143: added REST API for server groups

Change-Id: I11eb4a39445baaa15a05bb36390e1bffdb59e2dd
Reviewed-on: http://review.couchbase.org/29868
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
MB-1143: refresh pool details on server group updates

I.e. so that ?v trick works

Change-Id: I46f6b9feb8f212aafc1238d1899a2f841bb10fd6
Reviewed-on: http://review.couchbase.org/29869
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
MB-1143: added internal unittest for server groups API

Change-Id: I83d70fd86ceb75c1a5dbc277b64edce9530bd134
Reviewed-on: http://review.couchbase.org/29870
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
MB-1143: added api doc for server groups REST API

Change-Id: Iabaaa4383568df4146808e312074f49873acab1e
Reviewed-on: http://review.couchbase.org/29873
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
MB-100: corrected typespec for ns_cluster:do_complete_join

Somehow R14's dialyzer suddenly started seeing that obvious issue.

Change-Id: I4f300a6ba92b5b5254f38fd7b7f881ca9da32a96
Reviewed-on: http://review.couchbase.org/29879
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
MB-1143: enable adding 2.5 nodes to 2.0 clusters

Change-Id: If58bc3a30a6b3a7ec6583af9806a0b320169e63a
Reviewed-on: http://review.couchbase.org/29880
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Merge branch 'for-rackaware'

* for-rackaware:
  MB-1143: enable adding 2.5 nodes to 2.0 clusters
  MB-100: corrected typespec for ns_cluster:do_complete_join
  MB-1143: added api doc for server groups REST API
  MB-1143: added internal unittest for server groups API
  MB-1143: refresh pool details on server group updates
  MB-1143: added REST API for server groups

Conflicts:
	src/menelaus_web.erl

Change-Id: Id478fe864f0b28448b1a4fc3e01e18ea148e6fcf