Added draft of thread pool with timeout on each task.

See also:
-
http://stackoverflow.com/questions/2758612/executorservice-that-interrup
ts-tasks-after-a-timeout
-
http://stackoverflow.com/questions/4917039/how-to-ensure-garbage-collect
ion-of-a-futuretask-that-is-submitted-to-a-threadpo
- http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6602600
-
http://stackoverflow.com/questions/1800317/impossible-to-make-a-cached-t
hread-pool-with-a-size-limit
-
http://stackoverflow.com/questions/6714322/java-what-happens-to-runnable
s-that-hang-in-threadpoolexecutor