initial implementation of @ShadowService as well as fixes to connection recovery with SSE

Conflicts:
	errai-ioc/src/main/java/org/jboss/errai/ioc/rebind/ioc/bootstrapper/IOCGenerator.java
	errai-jpa/errai-jpa-client/src/main/java/org/jboss/errai/jpa/rebind/ErraiEntityManagerGenerator.java
	errai-marshalling/src/main/java/org/jboss/errai/marshalling/rebind/MarshallersGenerator.java
	errai-navigation/src/main/java/org/jboss/errai/ui/nav/rebind/NavigationGraphGenerator.java