How to run examples in README.md

### Pull Request Details
Never having worked with maven before, I took me quite a while of digging in the mailing list to figure our how to run one of the examples.
I think reading those examples is the best way to learn factorie, and running them should be one of the first things the user learns.

### Personal Introduction
This is my first contribution to an open-source project, so this pull request is also partly a test to see if I understood the workflow correctly.

I am using factorie for my bachelor's thesis at TU Berlin and hope to be able to contribute something substantial in the future. Can I just keep commiting small changes to documentation like this, or just I save up major changes and/or discuss stuff on the Google Group (or another mailing list?)

Thanks for such a great library,
Alec