After the refact of nova authentication in neutron, it supports
three auth_plugin: password, v2password, v3password. Each
auth_plugin match a different auth_url. For example:
a) password
auth_plugin = password
auth_url = http://127.0.0.1:35357/
b) v2password
auth_plugin = v2password
auth_url = http://127.0.0.1:35357/v2.0
c) v3password
auth_plugin = v3password
auth_url = http://127.0.0.1:35357/v3
The auth_url should be set following the auth_plugin automatically.
Change-Id: Ia584a6c6a64fcaa92012c957da004ac029ca7db2
Closes-bug: #1459594
Closes-bug: #1461480