Minor changes to config-persister to allow for karaf

These minor changes expose a ConfigPusher service for use
by a config-persister-feature-adapter (to follow) that
can push configs attached to features.

Change-Id: I382d2ab578d19ea9c24afa521a9a5a047360fc50
Signed-off-by: Ed Warnicke <eaw@cisco.com>
Merge "Minor changes to config-persister to allow for karaf"