[master] Fix for https://java.net/jira/browse/GRIZZLY-1550 (cannot deploy jsf on embedded grizzly: servlet initialization couldn't find Factory: javax.faces.context.FacesContextFactory)
  - Ensure the same ClassLoader is used to initializing the webapp and invoking the
     Servlets.
(cherry picked from commit 7b4de2786f36de280af90369ff816882b5f76716)