Aggregate and group indexer stats in a single step.
Aggregate and group indexer stats in a single step.

Change-Id: Ie590f61e20f6cea692b7dd4a2037bbb99df36456
Reviewed-on: http://review.couchbase.org/49488
Reviewed-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>
Tested-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>

nimishzynga/ns_server,ceejatec/ns_server,mschoch/ns_server,ceejatec/ns_server,membase/ns_server,nimishzynga/ns_server,membase/ns_server,membase/ns_server,ceejatec/ns_server,nimishzynga/ns_server,ceejatec/ns_server,ceejatec/ns_server,mschoch/ns_server,membase/ns_server,mschoch/ns_server,mschoch/ns_server,membase/ns_server,nimishzynga/ns_server,ceejatec/ns_server,mschoch/ns_server,membase/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,mschoch/ns_server