Permissions and security

We are not currently happy with the security system in infoarena, and a rewrite is planned (see #115, we haven't yet reached Kung-Fu Zen).

Here are a bunch of proposals related to security:

• CubeSecurityProposal: A complex database-backed ACL system, by fluffy.
• DirectorySecurityProposal: A filesystem-inspired idea, by wickedman. Not implemented.
• AntiMagicProposal: A proposal to decouple tasks and rounds from the wiki. Approved and reflects the current code.