Add "oob" checkbox?

[kadamwhite]

"oob" is a frustrating magical string, I've waffled on proposing whether to add a checkbox or not; so I bring that waffle to you all. Benefits to adding a checkbox to indicate an app is meant to be auth'd out-of-band: no magical string, clear signaling to the user. Drawbacks: possibly undesirable side effect of encouraging the use of the OOB flow, which is not preferred to the use of a callback when a callback is a possibility.