Extended permissions system

[zzzowoey]

Problem

Using Discord's permissions alone is really confusing from the end user's standpoint and doesn't offer enough fine-grained control over what the bot and/or guild members can do. I'd like to propose a new permissions system, and will be developing the idea more over time.

First steps and core ideas

These aren't necessarily in any sort of order.

• Completely do away with the use of Discord permissions in module declarations.
  I think we can probably find a way to deal with these upstream, but I haven't experimented enough with how Discord4J handles "insufficient permissions" errors.
• Offer a small set of clearly-named "access levels" that gradually offer access to more commands as you "climb the ladder"
• Implement a way to attach these access levels to certain roles and/or groups of roles
• Provide a clear, clutter-free interface for managing access levels and delegating commands
• Develop a system for storing these settings to the persistence layer