Can't store Unicode values in .matplotlibrc

[mdboom]

It is read in as a byte string on Python 2.x, and we don't do any decoding. We could just say its always utf-8. Or, for bonus points, read a -*- encoding -*- marker and use that.

[pelson]

This would be a great entry point for a summer student or for somebody who wanted to get involved with mpl development without needing to know a lot about matplotlib. For that reason, I'm going to add a "low hanging fruit" label to it (though it is a little trickier in terms of total effort than a normal "low hanging fruit" issue).