various fixes towards CompletedEvaluator error handling
Removed the wait in the idlehandler again
Aded a DriverExceptionHandler that forwards failures to the Client
Updated DispatchingEStage and EvaluatorManager to use the new ExcetionHandler
make a few variables final
move RuntimeErrorProtoHandler into a separate file and make is static again. ClientManager.runningJobMap is now synchronized
cosmetic fixes in ClientManager
Merge pull request #719 from Microsoft-CISL/sergiym_completed_evaluator_error

Fix the bug uncovered in FailDriverTest.testFailDriverCompletedEvaluator() test.
The build server error is bogus. This code compiles and runs on my machines just fine.