[API] removed JodaTime API

I know that the current Java Time API is worse. But using a 500 kb
library for just a "simple" duration calculation is much more worse
because it can be accomplished with the Java Time API without using the
deprecated methods.

Change-Id: Id7221866bde621ecb079885882f056f55cb0ea3d
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1179
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>
Tested-by: Jenkins CI