Remove skips in test server rescue

* Remove skips test_rescued_vm_add_remove_security_group
* Fixes two issues
    1. In remove_security_group pass self.sg_name instead of sg_id which was
        failing earlier.
    2. Before executing unrescue server operation, the server status seems to
       be active hence the bug 1126257. So adding a rescue operation at the
       start of the test to fix the bug

Fixes bug 1126257

Change-Id: Ie79b94b9cde0f35bb4ea5955bc284139d85123cb
1 file changed