MB-20852 [9/N]: Explicilty handle all queue_op uses

MB-20852 [9/N]: Explicilty handle all queue_op uses

Remove instances of switch statements where we don't check all
enumerations in queue_op, and instead handle them all. Makes it easier
/ safer to add any new queue_op types (and ensure they are handled
everywhere).

Change-Id: I9406c6d327d572268afa4d1830d690ee8ec153a1
Reviewed-on: http://review.couchbase.org/68161
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: buildbot <build@couchbase.com>