Extend images / instances tests
Run through auutopep8
Merge branch 'master' into generic-describers

* master:
  Run through auutopep8
  Extend images / instances tests

Conflicts:
	ec2stack/providers/cloudstack/images.py
	ec2stack/providers/cloudstack/instances.py
	tests/images_tests.py
	tests/instances_tests.py
Add describe zones