OMG! It's rubocop! And he's walking with a cane!

I've chosen to enforce the rules on our specs as well as prod code.

The only real consequence of this is our specs now prefer to be of the
form

```
describe M:N:C do
end
```

as opposed to

```
module M
  module N
    describe C do
    end
  end
end
```

I actually sorta like this style better anyway.  The only downside is
we must qualifiy references to `C`, or else use the handy
`described_class` method that rpsec provides.