Upgrade and new features

Hi there,

I made some changes to your plugin because I noticed that it broke each time that I was calling grunt with -v flag. In fact I use ```grunt -vd --stack``` when debugging, and it broke my build all the times.

By digging into your code, I then noticed that the error came from the usage of the **files** attribute of the task configuration object, that was not compliant to the [files object described here](http://gruntjs.com/configuring-tasks#files), perhaps because your plugin was developed with an older version of Grunt.

I took the liberty of modifying your code in order to leverage the automatic globbing pattern performed on the files config object, which is very useful inside a multitask, and in [expand](http://gruntjs.com/api/grunt.file#globbing-patterns).

This involved some smalll changes in the task config object, but I modified the example in ```./www``` accordingly.

I also added an option for minifying or beautifying (default) output.

Have a try and let me know.

Best regards,


Vito Macchia