JCBC-343: Adding Listeners support.

This changeset builds on the foundation of spymemcached
(ticket SPY-132) and adds functionality for replica gets,
and views (http futures).

Change-Id: I1a2b189947484555e0d51654913d0dd9681de9dc
Reviewed-on: http://review.couchbase.org/28109
Tested-by: Michael Nitschinger <michael.nitschinger@couchbase.com>
Reviewed-by: Michael Nitschinger <michael.nitschinger@couchbase.com>