This change introduces support for [clients] parameters and
[clients_<service>] parameters, which determine behavior of service
clients used by heat for communication with the OpenStack services.
- Implementation of heat::clients::<service> are generally same.
Only cinder, heat, keystone and nova provides additional parameters.
- The existing parameters in the base heat class are deprecated in
favor of the new classes.
Change-Id: Icdf4f0201dd1e5f93a450473709851977ec20034
0d043d793f