Add Reaction Roles

[7bitlyrus]

Reaction roles would be an awesome thing to have, I just haven't gotten around to adding them yet.

Proposed commands

• !reaction list (channel/message) - List all reaction role messages on server/in channel, or roles for a message
• !reaction create (description) - Create a reaction role message in channel
• !reaction edit (description) - Edit message description of and/or move reaction role to new channel
• !reaction role id role [emote|"remove"] (description) - Add role to reaction role message with emoji (and role description), or delete role from message.
• !reaction delete id (force) - Delete reaction role message, all roles should be removed unless force flag is set

Proposed database data structure

message_id: {
    channel: channel_id,
    description: str,
    editors: [id1, id2, id3],
    last_modified: time,
    last_interacted: time,
    roles: {
        roleid: {
             emote: emote_str
             description: str
        }
     }
}