Flavor should be pushed into Sentry

I think it would be very helpful to have directly the flavor pushed with log entries into Sentry.

For instance, it would help understand where a message is coming from and capturing context. If something is going wrong, like an EC2 plugin message for a docker-cloud flavor, we would understand it much quicker.

(Technically: we do have that information in the DB, from the UUID, but it's not accessible to anyone and would require one more hop each time).