Add interactive prompt to all auth'd commands. (#140)
Add interactive prompt to all auth'd commands. (#140)

* [exp] Add interactive prompt to all auth'd commands.

Users can specify the `--non-interactive` flag if they need to have the command fail (for example for CI).

* [exp] Print 'already started' error as an error instead of warning.

fbshipit-source-id: 0b13d73

exponentjs/xdl,exponentjs/xdl,exponentjs/xdl