Added Trove (Database as a Service).

Add basic Trove integration to devstack
- Added changes to stackrc for the Trove Repos.
- Added support to devstack for "install", "configure",
  "init", and "run"

Currently Trove is in incubation but it needs
to have basic support in devstack to provide
automated deployment / testing.

Fixes blueprint:trove-devstack-integration

Change-Id: Ib3f6daad33e629f764a174b80762c808ce8588e2