Do not pass endpoint to constructor in OSC
Do not pass endpoint to constructor in OSC

The constructor is using a Session. This means that an endpoint is not
needed. Further, passing one breaks things like the token_endpoint
plugin for OSC which do not have an auth_url. Just let the session do
its work.

Closes-bug: #1551837
Change-Id: I82dc42c31637f318682faa4383c4103abb5d9624

NaohiroTamura/python-ironicclient,openstack/python-ironicclient,NaohiroTamura/python-ironicclient,openstack/python-ironicclient