Grunt, bower added

First of all, really nice job you have here. Congratulations. 

I've just made a few changes

Grunt, bower added.
Changes:
 - Add a Gruntfile.js for source building and minifying.
 - Add a bower file for pandajs bower package
 - Change _loadScript function. The path now loads without /src/
 - Add a example folder with the panda game example

Source generation now becomes easy with npm:

    npm install
    grunt