bug 1512 - don't leak timeout_event registrations
bug 1512 - don't leak timeout_event registrations

Previously, if the code encountered a not-my-vbucket error
and wanted to retry the command, it would leak a libevent evtimer
registration, which eventually led to moxi pegging 100% cpu
with all the timer events.

Change-Id: I3d966246713b2c095b17ff2ffacb9943e2b90c87
Reviewed-on: http://review.northscale.com:8080/813
Reviewed-by: Eric Lambert <7ef4e71cebb32cb5e304f9d7d27d812f8d7da939@gmail.com>
Tested-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>

couchbase/moxi,steveyen/moxi,membase/moxi,couchbase/moxi,steveyen/moxi,membase/moxi,membase/moxi,steveyen/moxi,steveyen/moxi,membase/moxi,zbase/moxi,membase/moxi,couchbase/moxi,couchbase/moxi,membase/moxi,zbase/moxi,zbase/moxi,zbase/moxi,steveyen/moxi,zbase/moxi,couchbase/moxi,couchbase/moxi