[zaptel] /dev/zap/* do not belong to group dialout when using udev

[Jérôme Warnier]

When using udev, /dev/zap/* do not belong to group "dialout".

/usr/share/doc/README.Debian suggests to read README.udev, but there is
no such file.

It also suggest to use a file in /etc/udev/permissions.d/, but it has
been deprecated before Sarge.
udev's changelog says the following:
"""
udev (0.051-1) unstable; urgency=low
...
  * Updated the rules files to include permissions.
    The permissions files do not exist anymore.
...
"""

Thanks