[DONE-10] Wiki theme in OSEG Design

OSEG Organisation, Vereinsarbeit, Planung IT, Web, Software
#1

Update the Wiki theme with the new OSEG Design - Logo and colors.

Before that:
TODO: Make a page in the Wiki with all Corporate Identity information.

#2

I started that over here: http://wiki.opensourceecology.de/wiki/Corporate_Identity

#3

Theme changed to green.