Ensure lists works well on D7

Things that still need to be done on the Lists submodule:
- Newsletter (forum->email) subscriptions, and code that restricts posting access to these forums
- Git integration - the "maintainer news" subscription is required for all project maintainers

Status update:
- I tried to test the Newsletter subscription functionality, but the dev sites have newsletters disabled (the lists_* variables are missing -- which is by design since we don't actually want dev sites to subscribe people to the lists or send messages to the lists!), so I wasn't able to test subscribing or unsubscribing. The errors in the log indicated it was probably trying to do the right thing.
- Similarly, the forum post -> mail functionality cant' really be tested.
- I did test the functionality that restricts posting to certain forums for people without permission. That seems to be working properly (with the attached patch).

So... To dos left:
- Test the mailman integration with forums (subscribe, unsubscribe, post to list via forum post).
- Maintainer News newsletter (should be automatic for all project maintainers; test when project/git are ported).

When the attached patch is ported, the rest of this issue should be set to "postponed".

I'll be testing today.

Ran out of time today. I will take a look this weekend at the PNWDS.