[STF] cleanup of Contants class

Just a "Topfen auf den heißen Stein" ...

Applied changes that were necessary for the contact -> buddy revert
patches.

Change-Id: I1e295b39766130c549cbe51e3cb076ed533f9ada
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1198
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>