JCBC-491: Add support for counter and through the LongDocument as a result

Change-Id: I1dbac4c705a52855f14554e1061474a124c387b6
Reviewed-on: http://review.couchbase.org/39351
Reviewed-by: Michael Nitschinger <michael.nitschinger@couchbase.com>
Tested-by: Michael Nitschinger <michael.nitschinger@couchbase.com>