The attached article contains information on German and askari uniforms from East Africa. It was compiled by Matthias Schneider as part of an nvestigation into the possibility of a battle re-enactment at the request of Howard. The conclusion of the investigation/discussion is that a re-enactment at this time is inappropriate.
Other places to look for information on uniforms (thanks to Leon):
“The German Colonial Troops,1889-1918″by Kraus and Mueller