'Announce' email list for thedatahub

[dread]

We want to make email announcements to users of thedatahub.org.

The most simple way to do this is to get a dump of the email addresses and subscribe/invite them to a mailman list.

Different ways to do it:

• 'paster dump-users-csv' creates a CSV file. Apache serves up the directory using password protection. Is this secure enough?
• CKAN admin pages provides a button to produce the CSV and download it. A config option may be necessary to enable this (disabled by default).

Something more advanced in the future could be:

• CKAN tells mailman about new subscribers using the mailman web interface. Could be brittle.
• Mailman doesn't have an Internet API, but it does have a python interface. So CKAN could tell mailman about new subscribers using a python proxy. There may be one out there, or maybe easy to do. But annoying to have to maintain another process running on machine.
• CKAN sends out the emails itself. A sysadmin is given a form. Users have an opt in/out option in their account. But receiving emails is a sensitive thing so it would need to be right first time, and there are several risks to this approach.

[dread]

Rufus says that the paster command is enough for now.

[dread]

Code done in [master 804b549] headed for release

Example usage (on the appropriate server):

paster db user-dump-csv /tmp/users.csv