Fixes #5

Not ready for merging. Here for review. See #5 and https://github.com/yeoman/yo/pull/167. Better ideas are welcome!
Strangely, I did not have luck with `ansi-regex`.

`/(\x1B\[[0-9]{1,3}(?:;[0-9]{1,3})*?[m|K])+/g` worked, while
`/\u001b\[([0-9]{1,3}(;[0-9]{1,3})*)?[m|K]/g` didn't.