BUG-1617 AUthProvider implementation for ODL netconf backed by CredentialAuth

Added bew Karaf feature for aaa-authn-odl-plugin.

Change-Id: I41fcf61c17da9d40a9f090a5a5d334125d36aab5
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>
Signed-off-by: Ed Warnicke <eaw@cisco.com>