Add examples of using the API to the docs

[peplin]

This lib is mostly focused on the command line tools, but underneath is a capable API that developers can use to build their own apps. As Paul pointed out in the Google Group, we could use some good starter examples in the docs.

[peplin]

I just added some basic docs on using the interface and receive callback. Next up is the Vehicle class, but I think that needs unit tests before I'm really comfortable recommending people use it.