update v3 domains - remove public/private namespace

removed the private namespace options that were lingering in create/update/tests
it should now adhere to the v3 api specs

Change-Id: I853c2b8a13bc657e9cd2a3f24e6eb7deb68a4c5c
Use v2.0 api by default in auth_token middleware

Fixes an issue that crept in with d782a99 where auth_token
started defaulting to the v3.0 API by default when no version
was specified.

Given that bin/keystone still defaults to using the v2.0 API
it seems like auth_token.py should too.

Fixes LP Bug #1154144

Change-Id: Ia5620bccc182bbc73cb60dcccb1f701304450e5a
Retry http_request and json_request failure.

Temporary network outages or keystone server restarts can lead
to a connection refused in auth_token middleware. Rather than
failing immediately, this patch attempts to retry a few times.

Fixes bug 1150299

Change-Id: I2ecf0d7745290976efcb3e3cd6511817a53d3e0a
Doc info and other readability improvements

A few good suggestions were made on the final round of reviews
on the previous patch to add v3 token support, but were not
implemented. This patch applies these, which should not create
any functional change.

Fixes Bug #1154768

Change-Id: Ie5408a5477d176bd28b2c385e49cd29b39c0de39
Merge "Use v2.0 api by default in auth_token middleware"
Merge "Retry http_request and json_request failure."
Merge "update v3 domains - remove public/private namespace"
Merge "Doc info and other readability improvements"