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.
@ehelms 
the task sometimes starts during rake katello:seed and katello:test
this seemed to be a solution that prevents the dynflow task from starting. 
(https://github.com/dustint-rh/katello/blob/qpid_events_dynflow/lib/katello/engine.rb#L40)