Create Dockerfile for running CI workloads in jenkins

@craftyguy I made a dockerfile that will execute the conformance CI test suites.

You can test the image at: otc-mesa-android.jf.intel.com:5000/majanes/conformance-ci:latest

I haven't built mesa with it, but I think that will not be hard to do. If I were going to do more pathfinding, I would set up a branch to run a full scheduler (build/test) against the image. The only way I can think of that creating a problem is if one of the testers doesn't have enough space... but the image is < 2G.

To fully test, I would need to install docker on all the systems, or create a bunch of special labels for a subset of systems. I'm happy to do that if you think it will simplify CI configuration or reduce maintenance costs.