[turba] Adding a driver

[Adam Tauno Williams]

I've created the file pogi.php in the horde/turba/lib/Drivers directory
and a source in horde/turba/config.sources that has "'type' => 'pogi',".

But the source does not appear in the list of addressbooks I can select
from,  which makes it a little hard to debug. :)

Is there something outside of creating the file that I need to do to
"activate" the driver?

I know something touches the driver since if I deliberately introduce a
typo I get an error when I go into Turba.

The driver is a wrapper around POGI (PHP OpenGroupware Interface) so we
can use Turba to access our OpenGroupware groupware server;
http://www.opengroupware.org.