Some modifications to make the user's life easier:

-  Added user properties to the workflow
-  Added a reference to the prior task run - TaskRun.previousTaskRuns will return a set of the TaskRuns that executed immediately prior to the current TaskRun.  Note that in the current source, this will never be a set larger than one, but it might be null if this is a starting task
 - Added a "TASK_STARTING" event that is executed immediately before the task is launched.
 - Added a manual auto-approval so that we don't have to wait for AWS to catch up