Cleanse sqlalchemy models
Cleanse sqlalchemy models

We had a 'SenlinBase' class which is only inherited by only some of the
DB models. This patch removes that class to avoid complicated class
hierarchy while making the model declarations more consistent.

Change-Id: Ie9a42e579f68e04ae8c76c71f17a682d74f47247

openstack/senlin,openstack/senlin,stackforge/senlin,tengqm/senlin-container,stackforge/senlin,openstack/senlin,tengqm/senlin-container