Reformatted _Gruntfile.js to be leaner and more readable

The goal here is to surface the editable tasks to the top of the Gruntfile and not bother the user with `mountFolder` and matchdep stuff which they will never touch.

I removed the `server` task to simply have the default be the server task.

I also made the array syntax consistent where any array with three or more members has each member on a separate line.