Test and support Listen archives+subscribers import

[socialplanning]

Test and support Listen archives+subscribers import

[ejucovy]

The zopectl script that I started writing for #6 now imports archives as well, using Listen's built in MBOX importer. It works very nicely. This was added in 615e8c9.

[ejucovy]

Listen's built-in subscriber importer is not sufficient:

1. The documentation around the code assumes an outdated subscribers.csv format with only three columns per row. The current format contains four.
2. The code itself does not consume CSV files. It merely consumes email addresses so the caller is responsible for parsing the CSV file.
3. The code does not handle the distinction between subscribers and allowed senders during import. It seems to assume that all entries from subscribers.csv represent full-fledged list subscribers.

[ejucovy]

I filed socialplanning/opencore-listen#1 to track the CSV-reimport problem upstream.

[ejucovy]

I filed #9 to track the tracking of the upstream issue. Gonna close this issue now.