22935c1177
This change adds a component registry which can be used by different components, such as executors, mergers and others to register themselves, report their state and store arbitrary runtime information. This is needed to e.g., monitor components or to share the "accepting_work" state of executors later on. Change-Id: I4b7197d6cb399513e30d314f8a5f4f55ad9266f8