Updated grunt to 0.4.0

Updated Grunt to 0.4.0 version referencing the #135 issue.

Basically grunt.js and grunt-config.js files cease to exist, since they are now combined in Gruntfile.js.

Another observation: I'm now using YUI Compressor to do the JS and CSS minification and their file concatenation, so we reduce npm dependencies and it's easier to manage.

Due to the use of YUI Compressor, when the CSS files are joint their are also minified as you can see in the code attached. This happens at the same command now, I hope this isn't a problem.

Also, I tried to keep the docpad.coffee functions working properly. Please take a look at those.

If you have anything I need to change, please let me know.