addTracks update, README example and reran grunt

Just a couple of small changes, @JulioV did all the hard work in #9. I had run into this bug but had placed a separate fix in addTickPoint, this suggested solution is a lot simpler and the correct way to do it.

Also a small one but there was a reference missing in one of the examples in the README.

Finally i reran grunt to pick up the changes that were made recently. (Which also picks up #5 by @dgorissen)

Good work on the library!