Polish disable repository documentation
Polish
Improve Jetty third-party integration support

Make JettyEmbeddedServletContainerFactory more useful for third-parties
by providing protected configureWebAppContext, addDefaultServlet and
addJspServlet methods that sub-classes can call.

Fixes gh-1056
Merge pull request #1060 from akhikhl/master

* pull1060:
  Improve Jetty third-party integration support