8136930: Simplify use of module-system options by custom launchers
Reviewed-by: alanb, ksrini, henryjen, sundar

8150173: JAXBContext.newInstance causes PrivilegedActionException when createContext's declared in abstract class extended by discovered JAXB implementation
Summary: trivial fix - the concrete class must be instantiated, not the class that defines the createContext method.
Reviewed-by: lancea, mchung