Beautify upgrades' and achievements' numbers

Fixes #47

Fixes things like this one:

{
  name: "Let's never bake again",
  desc: "Bake <b>1,000,000,000,000</b> cookies per second."
}

I don't think anything else needs running through this, and I don't
think we need to do it more than once per script run, but I can add them
if that's necessary.