Added Grunt v0.4 build tool

* use 'grunt concat' and 'grunt uglify' (based on concat files) to recreate build/ files. ('dist', 'css' and 'box2d' builders for each one)
* deleted version.* scripts
* added grunt@0.4.0rc7, grunt-contrib-concat, grunt-contrib-uglify, grunt-contrib-jshint and grunt-contrib-jsdoc in node_modules/
* TODO: jsdoc create documentation in /doc without structure (based on caat.js)