NCBC-229: Add Remove with CAS overload and tests

Change-Id: I00b326c97d42fbbe3f806b86e3e5b252d9afd30d
Reviewed-on: http://review.couchbase.org/24713
Tested-by: John C. Zablocki <john@couchbase.com>
Reviewed-by: Saakshi Manocha <saakshi.manocha@globallogic.com>
Tested-by: Saakshi Manocha <saakshi.manocha@globallogic.com>