Feature Request: Set default number of reviews required and override for github labels

[jeremyricketts]

On our team, we use the label EZ on a PR, if the change is so small, it only needs one review (rather than the usual 2). It would be rad if ReviewBot didn't keep asking for a second review for those types of PRs. Since the label may be different for every team, it seems like it would be cool to make this a configurable setting.

Maybe we could set a default and then override per github label? Thinking outloud:

"reviews_default": 2,
"labels": [
      {
        "important": 3,
        "EZ": 1,
      },