MB-10069: Handle UPR expiration command

An expiration is handled the same way as a deletion. For both
the indexer and XDCR it doesn't matter whether an item was deleted
or expired, in both cased it should get removed.

Change-Id: Ic1de905aa2e9ae6dd09b386dc767710f89a546a2
Reviewed-on: http://review.couchbase.org/33036
Tested-by: Volker Mische <volker.mische@gmail.com>
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>