Start of a class to track statistics for executor.  To be used primarily in performance debugging and tuning.
Start of some stat tracking, and some getters to get those stats out of this class
Fix for check style warnings.
More statistics to be tracked
Fixed some bugs and added a little bit of unit testing to the stats tracking
Implemented unit tests for reusing threads.
More statistics and unit tests
Added statistics tracking for how long it takes for tasks to be ready to execute, and when they actually execute
Merge branch 'master' into unstable_staging