Support a dictionary to be applied to the task's "command" in a "custom" TaskFactory #374

Improvement Request Description

• When the generate yields a tuple with more than a handful of elements to be applied to the task's command it is hard to read/understand the command
  Example: command: /bin/bash -c "echo {0}; sleep {1}; echo {2}; executable {3} ..."
• It would be easier to understand if the above command could be written like
  Desired Example: command: /bin/bash -c "echo {calculation_result}; sleep {sleep_time}; echo {message}; executable {program_args} ..."