Revert "core: Remove dependency on scheduler"

This reverts commit 71b4d4223a786d6812186a236f86cac2bf39b3d3.

Change-Id: I3e47e9ce291a78cb9612bd0d32f6aca1cde5faee
Signed-off-by: Yair Zaslavsky <yzaslavs@redhat.com>