complete rewrite for grunt 0.4.0

- runs with grunt 0.4.0
- tests changed to grunt plugin style using grunt task nodeunit
- adding banner, footer via options (like in grunt-contrib tasks - concat, uglify,...)

same tests like in current release - just run:
`grunt test` (or `npm test`)

PS: thanks again for the rigger tool!!! Would be great if it would be added to grunt-contrib.