Grunt build process

Here is how the build process works:
1. Clean - Delete the .min.js and .min.css files from the public/css and public/js folders and the previous user scripts.min.js
2. Uglify - Any user js in the public/js folder
3. Concat - Concat bower files and user js and css files

Pretty simple. Keeps things to one http request. Let me know how I could improve! Thanks!