Default to whatever GitHub PR integrations are enabled, don't require a bors.toml file

[frewsxcv]

Speaking for myself, the only integrations I have (besides bors-ng) is Travis CI. The only status I care about is Travis. Could bors-ng just default to whatever statuses are enabled on a repository as a default and a bors.toml can be used to override that? This means that with most of my repositories, a bors.toml is not needed.

[notriddle]

Does #102 look like an acceptable way to do it? GitHub doesn't really give me a list of all integrations on a repo (doesn't help that Travis is currently a "Service," and "Services" are being deprecated). I can figure that you want to use Travis if you have a .travis.yml file, though.

[frewsxcv]

Does #102 look like an acceptable way to do it?

👍 💯