Handle the outputs logic, run monitoring in thread, and make record types configurable

[asmacdo]

Adds:

• --outputs
• --capture-outputs
• --record-types
• Tests for process_outputs

Runs the monitoring loop in a thread, which should prevent monitoring from blocking the main process, but this is not tested.

[asmacdo]

This PR should close out the last of the "smon redesign" checklist https://github.com/con/duct/issues/3

[yarikoptic]

yeay -- I see some tests being added. Good! Let's proceed so it is easier to review subsequent changes and try duct. So I will merge