NCBC-579: Make unsupported memcached methods throw NotSupportedException

Change-Id: I2a90ffef1ef612195aa19632d2b561a958944e20
Reviewed-on: http://review.couchbase.org/41156
Tested-by: Jeffry Morris <jeffrymorris@gmail.com>
Reviewed-by: Mark Nunberg <mnunberg@haskalah.org>