New CustomStyles arstian command, to allow saving custom client styles post deploy.

Took a bit of messing around but works great. Once merged we'll need an issue added for @blisteringherb to add a post deploy capistrano command to run `php artisan custom-styles`.

Resolves #325 (last item in checklist)

@angaither 

CC: @barryclark @DFurnes 
@weerd Yeah, it looks good to me