feature/sketch kore java interface

**please review**

Mostly sketches of the main data structures. We'll have to use them for a while to make sure everything is in order.

Also, once the interface stabilizes a bit (after we use it for a bit) I will document how to use it on a wiki page. For now, consider the examples as being the documentation.
this pom should already have access to junit 4.11. You shouldn't need this.