Add CI for hubot

[vlymar]

We rely on chatops pretty heavily, so it seems prudent to treat this repo the same as any of our other important repos. It doesn't have tests, but it'd be nice to be able to deploy to heroku just by merging to master.

That might be a bad idea because devs are used to master just deploying to staging. We could even have a staging version of hubot up and running, that only listens to commands in a special slack channel, and then use hubot itself to redeploy hubot (which would merge master to a production branch)...but all that might be overkill.

Still, it sucks to have to install heroku toolbelt and use heroku deployment flow, because we don't use that for anything else. deployment should be standardized.