Feature: Inactivity check, nudge, and possible kick

[erikkristoferanderson]

Bot will track when server members last sent a message in any channel. If a certain time has gone by with out a message, say two weeks, bot will send a nudge message. That message will ask the member to click a button to confirm that they want to stay in the server. If the member does not click that button, and another span of time goes by, say another week or two, the member will be kicked from the server.

Note: as a trial, maybe implement everything but the kicking feature. Or maybe instead of auto kicking, bring the matter to the attention of server mods.