Added submodule support

This should fix #6. It works by reading the .gitmodules file. It generates a three more requests but I wasn't sure how else to do it. 

It just links to the repo. I wasn't sure how to add a second link to the commit but the url is there to do it.
f.e. [core](https://github.com/Famous/core) @ [e97a327](https://github.com/Famous/core/tree/e97a327c7c91ba908ff3e8fd1e2115a09efa28bb)