BUG-865: prepare to move ListenerRegistry

This will evacuate the concepts.util package, guiding users towards
plain util package.

Change-Id: I9b600761f6cd7950b366e2bf40fd85f4bc8d5e9b
Signed-off-by: Robert Varga <rovarga@cisco.com>
BUG-865: move ClassLoaderUtils into util package

Removes the two previously-deprecated instances, deprecate the third one
and instantiate the utility at the proper place.

Change-Id: Ic9936326fb0f4d4b2129562ae84b131b79746c23
Signed-off-by: Robert Varga <rovarga@cisco.com>
Merge changes Ic9936326,I9b600761

* changes:
  BUG-865: move ClassLoaderUtils into util package
  BUG-865: prepare to move ListenerRegistry