Add Designate DevStack/Requirements/Docs Jobs

All new jobs are initially non-voting.

Create a new gate-designate-devstack-dsvm job, and apply it
to the check/gate queues of stackforge/designate and
stackforge/python-designateclient

Switch designate and python-designateclient to use the
python-jobs template, which brings in a new gate-{name}-docs
job.

Finally, enable the check-requirements template for designate
and python-designateclient.

Change-Id: I93ae46e3b7fea4a3115b9891d733215964419a38
Merge "Add Designate DevStack/Requirements/Docs Jobs"