Move tuyau.message to tuyau.document

Also, rename "enqueue" to "save".
Clean up old CouchDBs

This is still an incomplete copy of pytest's make_numbered_dir -- it's
not thread/process safe, racy, etc.
Fix dumbserver test

The application called "work_laptop" wasn't getting things because it
didn't happen to have any listeners. Now listeners actually filter.
Conditions can serialize to JS