CBIDXT-23 Indexer Implementation

admin_manager.go and cluster_manager_sender.go are stubs right
now for future implementation

Change-Id: Ic511e158bc23215c3f7bdaa752f99b41244c540a
Reviewed-on: http://review.couchbase.org/38578
Reviewed-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>
Tested-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>