Remove app.yaml, we will instead use web.xml and appengine-web.xml directly

* app.yaml is not well supported for java, the recommended method is to use
  web.xml and appengine-web.xml directly rather than generating them
* Specifically the appengine maven plugin does not play well with app.yaml
Merge pull request #257 from curtisullerich/remove_app_yaml

Remove app.yaml, we can instead use web.xml and appengine-web.xml directly