allow running gwt in dev mode with in place resources

When running gwt in dev mode, we want to be able to serve the GWT module with the in-place war hosted by the project. The application modules war should be contributed to our gwt component at runtime.

This will enable us to run the GWT code server concurrently with the nuxeo's SDK. This way we could remove the nuxeo's GWT dev launcher which introduce duplicated classes with the gwt-dev provided classes.