NCBC-613: Refactor operation result classes...

Change-Id: I66dfb4e25e2b9e4af4b77adda1eb5506014db173
Reviewed-on: http://review.couchbase.org/41085
Tested-by: Jeffry Morris <jeffrymorris@gmail.com>
Reviewed-by: Brett Lawson <brett19@gmail.com>