More rubocop

@localshred follow up from the last PR. This gets us nearly all the way to rubocop-completeness, but more importantly, it makes the tests run again, which I broke in the last PR :(
Slight complication: can't use single quotes because of the trailing newline. The style guide has the following to say:
https://github.com/bbatsov/ruby-style-guide#percent-q
https://github.com/bbatsov/ruby-style-guide#percent-q-shorthand