Install all iPython dependencies.

[flekschas]

I created a new virtual environment for the book's source code and only doing pip install ipython caused and error, when trying to open iPython's notebook, regarding some missing dependencies. I'd suggest installing all dependencies right away.

[softwaredoug]

Hey sorry I'm getting back to cleaning up our examples. I'm going to go through to make sure things install cleanly for folks with few headaches. If warranted I'll take your PR.