Code review/refactoring

Hi Alex,

@happy4crazy, @zmaril and I reviewed this (okay, maybe 3 people was overkill).

The biggest change was made to `new-proj`, which now mostly delegates to a new function `make-folders`, which was simplified to a loop.

We didn't continue on though due to a suggestion by @zmaril: the CLI component of regret should probably be a Leiningen plugin. (Leiningen provides a lot of the boilerplate you'll have to build up to create a comparable CLI.) Documentation can be found [here](https://github.com/technomancy/leiningen/blob/stable/doc/PLUGINS.md) and a reasonably simple example [here](https://github.com/ibdknox/lein-noir).

Cheers!