Allow usage of new Grunt 0.4 files syntax

I'd like to add support for the full range of files syntaxes, specifically the dynamic syntax:

http://gruntjs.com/configuring-tasks#building-the-files-object-dynamically

This also allows removal of the temporary normalization helper.

I've verified that all the current examples still work fine and I've added a new example showing the new functionality.

I also took the opportunity to do a bit of README cleanup (broken links) and general touchups.

I did bump the Grunt requirement to 0.4.0 final; that may or may not be what you want. I did not update this package's version as I am unsure of your desired increment.

Thanks very much for maintaining this package!