added custom reporters: xcode (default), json, csv. fixes #42

[jpsim]

Fixes #42.

Any interest in this from you, @keith or @jakecraige?

[jakecraige]

But I already wrote my clang parser!! https://github.com/thoughtbot/hound-swift/blob/master/lib/swift_lint/violation.rb#L3-L9

Now that this exists I'll probably switch to the JSON format since I trust parsing of that more than my large regex.

Thanks for this!

[jpsim]

Speaking of which, how are those efforts progressing? Anything I can do to help?

[jakecraige]

Things are going well. It's pretty much good to go but we still need to do some internal testing before releasing it into public beta.

With Swift 2 being out and having configuration, that should be happening soon. :)