Implement the other community types included in the original design doc

According to this doc there should have been 3 types of communities.

We have the first one, but still missing the second and third option:

1. Topic: anyone can post or comment
2. Journal: guests can comment but not post. only members can post.
3. Council: only members can post or comment

This has been discussed in this Hive Dev meeting and I'm opening the ticket to start a discussion