FELIX-2774, FELIX-2797 & FELIX-4424:

- implement support for including and forwarding requests using the Servlet
  RequestDispatcher, including several itests to verify behaviour [FELIX-2774];
- wrap HttpSessions in order to provide access to the correct ServletContext
  [FELIX-2797];
- rudimentary fix for possible classloader leakage [FELIX-4424];
- prepared the Servlet- & FilterHandlers for named servlet/filters;
- several fixes to make the HTTP implementation more conform the Servlet 3.0
  specification.



git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1567561 13f79535-47bb-0310-9956-ffa450edef68