[REFACTOR] Introduce AbstractResourceActivity

This pulls up the common functionality of all IResourceActivity
implementations.

Change-Id: Ibe7d4a0437c04c7c6bb0a6aa4f562912086655e8
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1525
Tested-by: Jenkins CI
Reviewed-by: Arndt Lasarzik <alasarzik@gmail.com>
Reviewed-by: Damla Durmaz <ddurmaz88@gmail.com>
Reviewed-by: Franz Zieris <zieris@inf.fu-berlin.de>