def run_time_or_time_elapsed
      if self.end_time         
         return Time.at(self.end_time - self.start_time)
      else
         return Time.at(Time.now - self.start_time)
      end
    end
def run_time_or_time_elapsed
      if self.end_time         
         return Time.at(self.end_time - self.start_time)
      else
         return Time.at(Time.now - self.start_time)
      end
    end
Creates run time based on start and end time
 If there is no end_time, returns time between start and now
 @return [Time] The run time object