Figure out RBAC model

[fairingrey]

It's not a super important issue at hand (as role/permission resolution will come more in handy later on in some sort of public alpha/beta) but I'm filing it here to eventually come back to.

[fairingrey]

General RBAC sketch-up thus far:

• Admin: Can do anything. Except maybe take down the public deployment or other destructive things.
• Moderator: Primarily manages users and secondarily content. Can free change roles up to any role below.
• Maintainer: Primarily manages content. Can freely submit content to the gallery with self-approval and approve content from other contributors (posts, tags, tag-merges, etc).
• Creator: Primarily manages their own content only. Can freely submit content to the gallery with self-approval.
• Contributor: Contributes content. Content submitted to the gallery requires approval by a Maintainer.
• Member: Contributes tags, comments and other related content. A Member can become a contributor after some threshold of positive contributions (voting tags that aren't removed, or other sorts of helpful content).