JCR-3745: Add JackrabbitObservationManager with additional methods for registering event listeners
JackrabbitObservationManager should extend from ObservationManager

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/trunk@1577242 13f79535-47bb-0310-9956-ffa450edef68
JCR-3747: Implement JackrabbitObservationManager
Initial implementation

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/trunk@1577244 13f79535-47bb-0310-9956-ffa450edef68