Updated Integration tests for openstack

It contains integration tests from https://github.com/opscode/knife-openstack/pull/86, https://github.com/ClogenyTechnologies/knife-openstack/pull/8,
https://github.com/ClogenyTechnologies/knife-openstack/pull/10
@muktaa Please review. Thanks
this seems to be used to identify test generated VMs for cleanup. With added support for metadata, we can use metadata instead of key. can you please file a leankit card?