Remove 404 link to novaclient in README
Remove 404 link to novaclient in README

The README had a link to
https://github.com/rackspace/python-novaclient, but this link is
404 now.

Change-Id: I538d65d2329ca1b4546e542513b7dbc536e6297f

Mercador/python-keystoneclient,sdpp/python-keystoneclient,magic0704/python-keystoneclient,klmitch/python-keystoneclient,darren-wang/ksc,darren-wang/ksc,Mercador/python-keystoneclient,klmitch/python-keystoneclient,ging/python-keystoneclient,sdpp/python-keystoneclient,ging/python-keystoneclient,magic0704/python-keystoneclient