Moderation functions

[atbrandt]

Though some of these features already exist in Discord in some form, being able to access them via chat commands in the bot can add a nice extra layer of usability. As such, the bot needs to support the following commands:

• Kick (with configurable "time-out" to create a temporary ban that will expire)
• Permanent Ban (with option to delete or preserve chat history from user)
• Set channel slow mode
• Mute (either from text chat, from voice chat, or from both)