!heylisten !begone - Dynamic server channel listening, sane defaults JIT

[jakethedev]

Ideas:

• startup should call util/discord:getAllActiveChannels and load them up before being able to respond to messages
• is caching fairly safe here? do we care about threadsafety? (if so, create another case for this like Battledao: commands that saveBattleState should be threadsafe #68)
• chat with others: is a minimal "always on" set of channels ok or stupid?

how to handle invite event?

• JIT set the values per call to getAllActive channels if none exist in the server BEFORE checking whether to respond

Blocker Notes

Currently blocked by server data cache #46 - this is mostly done though

Previously blocked by #30 and #31, the logic for this boils down really nicely, so it's just one case now

bot.js: handling dynamic channel listening
    if server not in serverdata: // this is just a getter and setter in util/serverdao
        get all channels from server // perhaps an abstraction can be built in util/discord
        save ID of all "defaults" found
        defaults in config.defaultChannels // FUTURE: when current servers all integrated, change this to like 3 simple ones for the docs
    if serverdata has channel id:
        if mod and message is 'begone'
            remove channel from server
        else
            run command
    else if mod and message is 'herebot':
        add channel to server