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.
@ehelms (and anyone else who's interested) - adding this dependency will break the ability to use the debian slaves for running katello test jobs, as the packages do not exist. @dustint-rh had a look for new packages, but we'd be building them ourselves, basically.

It's no problem to restrict the katello jobs to run only on the CentOS Jenkins slaves if that's what you guys want to do, but be aware you're reducing your pool of test slaves, which may make the wait time on tests larger.

Let me know if that's the way you want to go, I can restict the job easily.