Couchbase returner

Add a couchbase (http://www.couchbase.com/) returner! This one is available for use not only as a minion returner, but as a master returner (by setting master_job_cache: couchbase). This will allow you to go multi-master and have all masters maintain access to all minion return data.

This does require couchbase >= 2 as it uses the views.

In addition, I found some bug in the local_cache module where salt-call returns (from minions) were all being saved under the same jid ('req') instead of generating jids for them.