Improved support for node removals

If a listener is subscribed for removal events of a subtree, e.g. /a/b/c/d it gets removal events for everything in that three.
However, if /a/b is removed, the listener is not informed at all, which makes the listener state inconsistent/invalid
I suggest to add a new flag to the JackrabbitEventFilter and if that is enabled the listener will get remove events of all the parent nodes - if the listener is interested in remove events of any kind.