grunt 0.4.2 + explicit underscore

- in preparation for the eventual deprecation of grunt.util.* this refactors to use explicit requires for underscore and updates grunt 0.4.2
- I also took the liberty of removing the `~` operator in front of a couple of package.json dependencies.

I'm relying on unit tests, as well as manual testing of lineman-angular-template as my guide that this works (things were green/good for me) but would love some extra testing on this to make sure.

/cc @searls @jasonkarns