Updated user and group in debian params.

The havana release of horizon has the wsgi process
user and group as horizon in the debian packages.

Closes-bug: #1224770

Change-Id: I9a36ac12188d71721d16160055f3dc6fcd88b03e
Merge "Updated user and group in debian params."
Policy file paths on osfamily=RedHat have changed

On RedHat distributions of OpenStack (i.e. Fedora, RDO and RHOS),
the path of the RBAC policy files has been changed to differ from
upstream as they strive to have all configuration pieces under
/etc/openstack-dashboard instead of /usr/share/openstack-dashboard/

This change merely mimics the change Red Hat performed downstream:
https://github.com/redhat-openstack/horizon/commit/76e15a3cd419a0038b44687effec95b41e656d79

Change-Id: Ib1692244fed6191af84af0123c78129d71991a41