[INTERNAL] moved ActivityUtils class to core

Renamed to ActivityOptimizer.

Also deleted and moved test cases from Saros/E to the Saros core.

Change-Id: Ia4349a7c4471c4f481c8d0de02566193147f1d80
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1946
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>