Feature: Check (name OR email) rather than (name AND email)

[wbeckler]

Since DCO check lives in automated processes, it is especially painful when it fails in a situation that it shouldn't have. This can happen when someone changes their github name or their github email. To allow for that change to happen more smoothly, it could be better to check only one or the other. I think it still ticks the box that DCO is trying to tick, but it ticks it in a nicer way that allows for these kinds of changes without triggering unnecessary integration failures.