TimeoutFactory should expose thread pool

The TimeoutFactory should expose its internal thread pool for both programmatic configuration
and JMX management.

The current implementation is no conducive to this concept since it is a singleton.
To avoid potential backwards compatibility problems, I'd suggest writing a separate class
that can be exposed as an MBean (like the thread pool) with the old singleton class
using the new class for its singleton.

Also, since there are no adequete tests for this feature and it is used in a number of places,
a comprehensive set of tests need to be written to avoid breaking this class.