package/python-web2py: fix permissions

The PYTHON_WEB2PY_PERMISSIONS table was using the user and group names
instead of the uid and gid, causing makedevs to retrieve the uid and gid
from the host system.

Signed-off-by: Noé Rubinstein <nrubinstein@aldebaran.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>