Support unversioned endpoints in service catalog

[Brian Curtin]

At least on my devstack, I'm getting back an image service that is just a host and port, no "v1" or "v2" tacked on the end like everything else.

There's two things to consider here:
1. A GET / to that host:port returns detailed version information, offering further discovery.
2. We have implemented the image API against known versions, currently only the v1 API, so we could construct the base_path of image related resources with a leading /v1.

[Terry Howe (thowe-g)]

http://paste.openstack.org/show/158023/

[Terry Howe (thowe-g)]

 {"endpoints": [{"adminURL": "http://172.22.191.138:9292", "region": "RegionOne", "internalURL": "http://172.22.191.138:9292", "id": "1477cb8a07fa49d8967c64e6ded00711", "publicURL": "http://172.22.191.138:9292"}],

[Ian Cordasco (icordasc)]

We also now support v2 thanks to Steve. We could realistically choose either one based on availability.

[Terry Howe (thowe-g)]

Version discovery is covered in this blueprint https://blueprints.launchpad.net/unifiedsdk/+spec/version-discovery

I'm thinking this ticket should just be about unversioned endpoints.

[Terry Howe (thowe-g)]

https://review.openstack.org/#/c/153095/