making sure tasks that have timed out show up in the case log and that admins are notified. We are now signing up admins for all actions in the simulations they admin.
fixing bug in action::execute - it wouldn't work when executed outside an HTTP request (from the timeout sweeper). Now timeout tasks will have a null user_id which is not ideal. We might want to pass on the trigger type (time) to the case log entry to more clearly indicate when an action timed out.
