This SimObject can be used to quickly test the statistics are
functioning correctly. The SimObject schedules a single event which sets
the statistics to values dependent on the SimObject params.
With this commit the "Scalar" stats have a StatTester subclass that can
be used for testing. More can be added as required.
Tests are included to check our Scalar SimStat functionality.
Change-Id: I78fa5d9a0c3fc7115bd6c6d3410a5436aaa47f55