Update npm packages

The mismatch warning between local and global grunt was bothering me so I decided to update the packages.

As a sidebar, its probably worth considering using the `^` for npm packages. It's the node community standard and is what the command `npm install <package> --save-dev` does by default. Though I don't think that it's a good idea to leave them loose once something is deployed or if a team gets to be big it's probably worth going with convention for a seed project.

Thoughts?