Eventual plan is to move to Travis for CI, will add firefox then when possible.
Browser data for this semester suggests that firefox usage is rather small:
![screen shot 2014-01-04 at 3 03 21 pm](https://f.cloud.github.com/assets/920130/1845256/459f8736-757b-11e3-8a4d-f839665d90dd.png)