Restores r10014 (rolls back r10016), Makes EventBus available outside of the gwt
package

The GWT EventBus et al cannot be deprecated unless / until
ActivityManager and friends move to com.google.web.bindery.

Similarly, EditorDelegate#subscribe returns
com.google.gwt...HandlerRegistration rather than the new version. That
can change if / when Editor follows RequestFactory
to com.google.web.bindery.

Review at http://gwt-code-reviews.appspot.com/1421802

Review by: robertvawter@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@10018 8db76d5a-ed1c-0410-87a9-c151d255dfc7