S3 connection

[Tyrone Hinderson]

I was logging to S3 in 1.7.0, but now I need to create an S3 "Connection"
in airflow (for remote_log_conn_id) to keep doing that in 1.7.1.2. Rather
than set this "S3" connection in the UI, I'd like set a AIRFLOW_CONN_S3 env
variable. What does an airlfow-friendly s3 "connection string" look like?