Fixes #6543 - updt index on cp event bz1115602

This listens for entitlement events from candlepin and updates the specific
pool index instead of pulling all the subscription information each time
the user accesses the subscriptions page.

New gem dependency added: qpid_messaging
gem has dependency qpid-cpp-client-devel and qpid-cpp-client
rpm packages.
Being available on rubygems.org does necessarily imply that the RPM is available. We'll need to add it to koji and add it to our comps if this isn't available in the SCL or already being built.