Coq file dependency graphs

This is a first stab at most of what remains of #204 (I still want to figure out how to do http://ssr.msr-inria.inria.fr/~jenkins/annotated/).  Travis should now build us per-file dependency graphs of theorems.  There's an all-of-the-core-library, but it's horrible to look at, and there's an all-of-the-entire-library, but, uh, I think it breaks the tools we're using, so I commented out that target.  There's a very plain index file that we probably want to improve.  

Here is a preview, the graph for the circle:
![hott hit circle](https://f.cloud.github.com/assets/396076/2277184/4017bea0-9f3d-11e3-801e-3e3c3db03bb3.png)