Lint code prior to any mutation testing so it can be operated on by Muter

[SeanROlszewski]

Right now, Muter as a limitation that requires there to be spaces around operators so it can mutate them. The story is supposed to add a step that eliminates this limitation.

We can probably use swiftlint to do some very basic formatting of code Muter is operating on after it copies it to a temporary directory, but before it begins doing any file or mutation operator discovery.