Add heat.template for Redis datastore

Reasons:
- common policy for datastores:
       each datastore should be able to
       be provisioned as part of heat stack.

Changes:
- adding heat.template

Change-Id: I3b44c75b80da7b7b2a296259fbf925d5ec9d71a6
Closes-Bug: #1285157
Merge "Add heat.template for Redis datastore"