Streaming stdout includes diagnostics

[edsu]

It appears that diagnostic information is being written to stdout instead of stderr when streaming, which causes non-json data to be written to a file:

 twarc stream  > stream.jsonl

This put the following lines in stream.jsonl:

Started a stream with rules:
☑  kenmurestreet
☑  forcedeviction
Writing to <stdout>
CTRL+C to stop...