[Merge] lp:~jimmy-sigint/mailman/postfix_relay_domains_map into lp:mailman

[Jimmy Bergman]

Also, it contains a tiny change to the REST API to include list_id in the external list representation.

Since it is needed to be able to subscribe through the API it makes sense that you are able to retrieve it for a list.
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https://code.launchpad.net/~jimmy-sigint/mailman/postfix_relay_domains_map/+merge/125241
Your team Mailman Coders is requested to review the proposed merge of lp:~jimmy-sigint/mailman/postfix_relay_domains_map into lp:mailman.