Added VoiceStateUpdate handler and DataStore for VoiceChannels. Also added toString methods to Guilds, DMChannels, ServerChannels and Users.

src/structures/VoiceChannel.js

@@ -1,10 +1,12 @@
 'use strict';
 
 const ServerChannel = require('./ServerChannel');
+const VoiceChannelDataStore = require('./datastore/VoiceChannelDataStore');
 
 class VoiceChannel extends ServerChannel {
 	constructor(guild, data) {
 		super(guild, data);
+		this.store = new VoiceChannelDataStore();
 	}
 
 	setup(data) {