Changed Fix Version(s) to 1.8.1

The clean-up of resources associated with the specified ICEfaces ID is now delayed upon receiving of the ICEfaces ID disposed event. Marking this one as FIXED.

The implemented delay mechanism uses a freeMap for its administration. Upon receiving an ICEfaces ID Disposed event the ICEfaces ID is added to the freeMap with a current timestamp, but is not actually deleted yet. The logic to determine if an ICEfaces ID is valid changed into if an ICEfaces ID is contained in the sessionMap and not in the freeMap the ICEfaces ID is valid, otherwise it evidently is not. To further explain the implemented delay mechanism is invoked upon receiving any ICEfaces ID Retrieved event. The clean-up logic traverses over the freeMap and actually removes any ICEfaces ID with an associated timestamp equal to or larger than 60 seconds. Synchronization is being used in the appropriated places to avoid possible multi-threading issues.