Add gate-climate-devstack-dsvm

Initial non-voting devstack gate job for the stackforge project Climate.
The main purpose of this job is to test devstack integration before
adding testing to it.

Implements blueprint climate-devstack-gating

Change-Id: Ifa76365d849b51926422d3d85902a8a4a4fc250e
Merge "Add gate-climate-devstack-dsvm"