Add common messaging attributes

Similar to the way in which we handle database attributes, provide a
mechanism that allows for centralized messaging configuration. Right
now this supports rabbit, but there is no reason other message queues
could not be added in the default['openstack']['mq'] namespace.

This bumps the version to 3.0.1 and all tests pass.

Change-Id: Id9d34fa7c256920dd575eee57c7b3820dacf8068
Adding a networks module to openstack-common

As determining IP from a given interface name is probably
something that would be useful across repos, add this functionality
to a central place. Where better than here?

Change-Id: I06aeeb1d0d3cc3fe6bfc47947b1e7aff91a401ee
Merge remote-tracking branch 'remotes/origin/messaging' into hsmaster
Merge remote-tracking branch 'remotes/origin/networks' into hsmaster