Add travis-ci for automatically testing PR's + commits

[SEJeff]

@ThanosBaskous What do you think of setting up travis for aurproxy? That way any new PR will be unit tested as will any commits. I started playing with adding HEAD request support to the http healthchecker last night and will be updating the tests.

I'd be happy to make a travis config for you if you've never used it. Two other large open source projects I co-maintain have used travis successfully. The saltstack corp guys use a jenkins instance they setup internally to test their proprietary stuff, but they were using travis quite successfully awhile back.