options to add / rm misc proceseses, ~readme, minor refactorings

[aflansburg]

Why this PR?

I ran into issue where the fact that I had disabled my Steam Overlay (aka GameOverlayUI.exe) was preventing the server search & join from occurring. Also Matt is awesome and this is awesome, so I wanted to contribute 😉

What it do?

• Adds a processes.game_processes data struct in seeding.yaml to facilitate add/rm of game processes you might want to be running
• refactors a couple of functions

Did you test it?

• Yes I did. I did not write unit tests, but I manually tested it with the steam overlay process added/commented-out in the seeding.yaml config file.