Adding Bower support to the generator.

I still have more contribution in mind, but this will be the first for now. Not including Bower would be a "violation" to the rules of Yeoman.

Some minor changes are also added to the code as well. Capitalizing the H on Git(H)ub, and leveraging the already-installed load-grunt-tasks to load the specific Grunt tasks. The rest are just the matter of removing the local Bootstrap files and changing the file path.

And since I have just planned to try Assemble, there might be some way to put bower_components directory and the relative file paths pointing to it be controlled by Assemble itself, is it?