Bug 1034130 - add France/ZTE Open C to devices page

This image could probably just be called "zte.png" as there may be other ZTE phones that aren't limited to France.

The image could also stand to be optimized. I've attached an optimized version here. It's 40% smaller, but it was quite small to begin with, so it's not critical.

![zte-france](https://cloud.githubusercontent.com/assets/58062/3598414/6c19d188-0ce2-11e4-9932-4839c8936086.png)

The optimization and filename are both worthwhile, but if this is time-sensitive, neither issue should block it from going into production. r+ after those issues are addressed (or before, if it is a rush)