update german translation
update german translation

I removed some inconsistencies like using the word "User" instead of "Benutzer" in the german translation
stinnux/kanboard,libin/kanboard,filhocf/kanboard,Busfreak/kanboard,oliviermaridat/kanboard,libin/kanboard,patoi/kanboard,renothing/kanboard,fguillot/kanboard,thylo/kanboard,fguillot/kanboard,patoi/kanboard,BlueTeck/kanboard,BlueTeck/kanboard,oliviermaridat/kanboard,kanboard/kanboard,oliviermaridat/kanboard,kanboard/kanboard,stinnux/kanboard,filhocf/kanboard,filhocf/kanboard,patoi/kanboard,renothing/kanboard,thylo/kanboard,Busfreak/kanboard,Busfreak/kanboard,stinnux/kanboard,fguillot/kanboard,BlueTeck/kanboard,renothing/kanboard,thylo/kanboard,kanboard/kanboard