Enforced code formatting

[mynameisrufus]

I have been using https://github.com/bbatsov/rubocop in my code bases and am really happy with it. What are the chances of adding it to this one?

[jch]

I'm open to the idea, but would only run it against new commits and PR's because the existing code formatting is a mess.

cc @mtodd @schaary

[mtodd]

I'm skeptical of the value it adds, whether it will add massive amounts of noise (especially in the project's current state) or encourage styles that contradict our values to new contributors (more of a hypothetical) as I'm not a user of this library.

I'd be open to experimenting with it, though: it should be as simple as opening a PR with it added and wired up, the Travis CI builds should show us the results, right?

[mynameisrufus]

You can get it to generate a todo.yml that you can slowly remove the violations over time, I will make a PR for you to look at :)

[mtodd]

@mynameisrufus thanks!

[jch]

Added in #181