Moving host admin extension with other extensions

Think this was merged during the big api changes in g1. This allows the
extension to actually be enabled.

Change-Id: I07bb9646fd11368fe5ffd7f85617ecbf103dc788

diff --git a/cinder/api/openstack/volume/contrib/hosts.py b/cinder/api/contrib/hosts.py
similarity index 100%
rename from cinder/api/openstack/volume/contrib/hosts.py
rename to cinder/api/contrib/hosts.py