Add gate-murano-devstack job

Add an initial devstack job for the Murano project. This project
consist a few stackforge repositories.
It just installs murano's devstack integration and runs devstack.
That just ensures that the devstack integration doesn't blow up just
trying to start up the service(s). There's not much else to test yet,
but this is a starting point to build on.

Start this job out as non-voting so that we can make sure it works as
expected before turning it on to be gating.

Murano functional tests were moved to the correct directory with the
following commit: https://review.openstack.org/#/c/74998/

Change-Id: Id748e57aa72237cd62c13c1184b2c93f077cdcfc
Merge "Add gate-murano-devstack job"