Added fixes to help the gwt compiler locate the .gwt.xml files.

With these fixes at least the gwt compiler gets going on the sources generated. I still get lots of errors for missing sources related to libgdx which I suspect is because the source I've compiled locally are not the ones being pulled in by gradle (using the maven references). But since local file dependencies is a PITA in gradle I haven't find an easy workaround for forcing loading my local versions (yet anyway), short of changing all the build.gradle files (using "compile files(...)" references instead of the maven ones 'compile "com.badlogic.gdx..."'.