This branch contains two little changes to prevent failures to future image
uploads in wiki and correct the upload_to value for the admin site.

To read why this is needed see:
https://code.launchpad.net/~franku/widelands-website/handle_big_images/+merge/247235/comments/625062This
is 

part of
https://code.launchpad.net/~franku/widelands-website/handle_great_images/+merge/254988