fix getting token, message update, issue #83
fix getting token, message update, issue #83

* fix getting token when using email and password
* fix using message cache correctly and emit on `MESSAGE_UPDATE` again
* fix curly brackets on `VOICE_STATE_UPDATE` to set voice channel id only if present
* fixes #83
* remove unused parameter when calling `prepareAudio`
zaza7/discord.io,izy521/discord.io,izy521/node-discord