Added UMLGraph to javadocs.

What do you think of using UmlGraph in the javadocs? If you don't like it I can remove them. 

![screen shot 2013-06-12 at 6 36 06 pm](https://f.cloud.github.com/assets/1326504/646389/9c887bf0-d3ca-11e2-8135-69db2d2228f9.png)

Few examples:
http://arcbees.github.io/GWTP/javadoc/apidocs/com/gwtplatform/dispatch/shared/Action.html
http://arcbees.github.io/GWTP/javadoc/apidocs/com/gwtplatform/mvp/client/gin/AbstractPresenterModule.html
http://arcbees.github.io/GWTP/javadoc/apidocs/com/gwtplatform/dispatch/annotation/processor/GenProcessor.html

Thoughts?