Last modifications to work on OpenStack

As been tested with this : http://code.launchpad.net/~thomnico/charms/precise/dns/openstack-support

Worked on both EC2 and private openstack. Tested with sipml5 charm in the charmstore.

Please comment
Should we close down https://code.launchpad.net/~thomnico/charms/precise/clearwater-sprout/openstack-support/+merge/233709 and the related pull requests now?