Known field now handled at one location

Also added http status codes back in
Fixes

* Typo in Display books
* Scrollable view for book display
* Missing translation
Added client configuration

Someone might want to create her own WIR-Server instance, or be really
pressed for bandwith and select plain http. Also: account selection
FIX: Delete from memcache too

Maybe I should consider some kind of automated change detection after all
:/