the attached patch provides a new python module "pyhbac" that implements
python bindings for the HBAC evaluator library.
The patch depends on Stephen's last patches which are on review as of
now, but the test suite passed, so I think the bindings can be reviewed
"make check" loads the built python module from tree by doing some
sys.path magic. If you'd like to experiment with the module yourself,
you must either install it or set PYTHONPATH to $SSSD_BUILD_DIR/.libs