• Add test to check Buildbot master config

    This test can be run via `./test.py sls.buildbot.master`. It will only
    work properly once the Buildbot master states have been run, and is
    meant to be run either in Vagrant or on Travis, not locally.
    
    Running `./test.py` without arguments will only run the linting tests, since
    those can be run anywhere with just the source code.
    
    For now, hard-code this test to be run on the servo-master1 node on Travis.
    This should be replaced with a more intelligent test dispatcher in `test.py`
    which uses the top file via Salt's state.show_top in the future, but hard
    coding this for now will reduce Buildbot's fragility.
    aneeshusa committed Apr 7, 2016