Ability to append and pre-pend to Jobs

[computron]

After an Activity has already been created, ways to edit that Activity is often useful. This is because when you want to go "off the beaten path", you want to maybe use an existing ActivityMaker but don't want to adjust the arguments of the ActivityMaker to support whatever your specific requirement is. In that case, you want to just take an Activity from an ActivityMaker and modify it later.

For this, we discussed having ways to define a new Job that is either prepended or appended to an existing Job in an Activity. That way, we can perform certain custom setup, cleanup, etc. tasks for a Job without having to add a bunch of additional arguments in the Maker / Activity / Job.