Add appropairate authorization headers to test with SPNEGO too as
discussed in #48
Requires recent version of python-gssapi module, see:
https://github.com/pythongssapi/python-gssapi/pull/74
Simo: Squashed original patches in one, removed trailing whitespaces
and reworded the commit message.
Reviewed-by: Simo Sorce <simo@redhat.com>
Closes #49