Correct a German translation error in Exchange app

Corrects a German translation error in the Exchange app thus fixing bug 43079 https://code.google.com/p/android/issues/detail?id=43079

Rebase Mon 11th March 2013

Change-Id: Ie0d8cecbf8602ad0494ff5ca2c7f9db56184cd53
Fixes: bug Issue 43079 https://code.google.com/p/android/issues/detail?id=43079
Signed-off-by: Emma Sajic <esajic@effectivelateralsolutions.co.uk>