By priority:
- Getting it from the FREEZER_API_URL parameter in the enabled file
- Getting it from keystone with the provided endpoint type
- Getting it from keystone with the 'internal' endpoint type
- Getting it from keystone with the 'public' endpoint type
Resolves bug: 1541933
Change-Id: I7c369ca192f9c3acf551270382abb2bf231abb38