Ready API for more fine grained per-bundle notifications

k.faseela (in private email) expressed interest in infrautils.ready be able to report more fine grained per-bundle notifications. She would like to consume this in infrautils.diagstatus, and said specifically this would be useful for her:

org.opendaylight.infrautils.ready.SystemReadyMonitor should either allow another registerListener(), or we could directly extend the existing SystemReadyListener, to get notified not only of onSystemBootReady() as we have, but also onBundleActive(String bundleSymbolicName).

There is of course already lower level pure OSGi API for something lie this, but infrautils.ready should do it integrated with Blueprint - probably based on the odlparent TestBundleDiag thing (which may need an extension for this).