FELIX-4420 - Implement sendRedirect:

- implemented original idea of overriding sendRedirect with logic for rewriting
  relative and absolute URLs;
- added test case provided by [~chetanm] and extended it with some additional tests.



git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1635470 13f79535-47bb-0310-9956-ffa450edef68