Wiki: removed edit rights for unknown users

[Dimi Paun]

Folks,

We've got a lot of vandals lately on the wiki, and people
are doing quite a bit of cleanup for no good reason. So
I have removed the ability of people that are not logged
in to edit pages. In fact this has been in force for a
long time, but since we've upgraded to the new 1.5.x release 
of Moin, we reverted  to allow anybody to edit pages.

Please let me know if you encounter any problems or have
any concerns regarding this policy.