Always pass the router image UUID to Nova boot functions.
Add an optional parameter to `rug-ctl rebuild` for a custom image UUID.
Add tests for custom image rebuilds.
Retrieve custom image data from Glance to avoid bad image UUIDs.
Fix pep8 failures.
Merge pull request #179 from ryanpetrello/router-rebuild-with-custom-image

Support router rebuilds with a custom image