common: Implement ClusterInfoCache helper

ClusterInfoCache can be used to obtain information about node services,
node-bucket membership, node-vbucket memberships, current node, etc.

Change-Id: If7aac1bd17c6427dec6a64e48ecf9a7f641c959f
Reviewed-on: http://review.couchbase.org/43706
Reviewed-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>
Reviewed-by: Sarath Lakshman <sarath@couchbase.com>
Tested-by: Sarath Lakshman <sarath@couchbase.com>