Add Support for Grunt load config

Addresses @zgardner 's suggestion in #4

Splits each individual task in initConfig into it's own ```task.js``` file for improved maintainability. Tasks can be found in the ```grunt``` directory.

Adds [load-grunt-config](http://firstandthird.github.io/load-grunt-config/) as a dependency in package.json

Updates index.js to make sure each task.js file is processed when Yeoman scaffolds the project.