Minor refactor and adding a new script to add/remove server arrays from ELBs for red/black deploys

@diranged, siminm-nextdoor, wenbinf please review.
These script references are unfortunately account-specific ... meaning that these do not work on our Production account. I suggest you create a hash that has a mapping for production and engineering accounts. From there, you can choose which account you're operating in via a CLI switch.