Fixes #6543 - updt index on cp event bz1115602

DON'T MERGE UNTIL the following are merged:
https://github.com/Katello/puppet-qpid/pull/8
https://github.com/Katello/puppet-katello_devel/pull/14
https://github.com/Katello/puppet-katello 

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.
What does this do? AFAIK since we are an engine, this config.ru file doesn't get loaded and should probably be removed at some point.