Utilizes bower in test suite

This is an initial PR to illustrate how bower can be utilized. The `ext` folder is unchanged, but now the testing suite depends on the installed bower components, and not the files in `ext`. I also went ahead and updated Underscore to the latest version. jQuery might also be considered for upgrades to `~1.11.0`.

I suggest completely removing `ext`, and setting the dependencies to just be from `bower`. Then it's super easy to keep things up to date and it makes your repo have less unnecessary bloat. If you'd like me to do this I can go ahead and move forward with it, though I'm not sure how to work with anvil.