in GWT debug mode remove hop headers disallowed by Python 2.7

Added "hop headers" disallowed by Python 2.7 to set of
headers removed during the call, so one can use the gwt
forwarding for debugging with 2.7.

Signed-off-by: Julius Gawlas <julius.gawlas@hp.com>
README: Add link to mailing list and IRC info

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>