right alignment vertical labels

Hi,

nice lib, i added some Alignment for the Vertical Labels, so i can render Labels like shown there.
I added some method on the Style class to make this work easy. Also uses some constraints which will result in an exception when someone try to pass in Align.CENTER

I done know about your formatting settings, i used the "Eclipse Build In" formatter settings.

![pull_request](https://f.cloud.github.com/assets/1496440/1191765/64386b24-2457-11e3-9776-911f98760028.png)