make keystone.host point to controller_virtual_ip

Previously keystone.host was pointing to the local controller_host
which would have caused all local services to become unavailable
if keystone was to go down.

Closes-Bug: #1339986
Change-Id: I9b73595d3e0ae6e872aa6b7e0f93354ff04f2956
Merge "make keystone.host point to controller_virtual_ip"