Added a shortcuts module

This is a first stab, but it works decent enough from the testing I did. It'd be cool to make these configurable or toggle-able or something. 

Also, I added jquery to the content scripts section, which probably wasn't necessary but I don't think the performance problems are going to be too terrible for anybody using chrome. 

Let me know what you think.
I just copied that over to mine. I don't know what the update chrome extension process is like, but as far as github goes if you accept/merge my PR then you can apply your own changes on top of it. Or you can reject my PR and just copy stuff over I guess, but that would make me a :panda_face: