try wheels for faster dependency installation

Wheels built by me, and hosted here at Berkeley.

2to3 on pygments and docutils was adding 2 minutes to install time on Python 3.

I did not upload wheels for pyzmq because they did not import properly on the VM on the first try. But compilation does not take nearly as long as 2to3 (~15s).

Compare [before](https://travis-ci.org/ipython/ipython/builds/23957994) and [after](https://travis-ci.org/minrk/ipython/builds/23956791).