update grunt file to put everything in dist/dev and dist/prod. 

This pull gives us a dist folder similar to what was detailed in issue #21. The only difference is that I created a dev folder where css and js was not minified/compressed and a prod folder where they are. If everyone's OK with the changes I'll merge them.

Thanks,
Jon
Can't tell on github, but all the whitespaces changes here imply that you converted this to a file that uses tabs for indentation or something? This project uses spaces for indentation. See `/.editorconfig` - http://editorconfig.org/