Turns out some people would rather edit local files in /etc rather
than shipping them in a package (as e.g. Fedora does with the
polkit-desktop-policy RPM).

This also drops the hard-coded list of directory names such as
10-vendor.d, 20-org.d - we now monitor the
/var/lib/polkit-1/localauthority and /etc/polkit-1/localauthority
directories for changes - whenever we see a subdirectory in any of
these directories, we create an AuthorizationStore object that looks
for .pkla files.

Signed-off-by: David Zeuthen <davidz@redhat.com>