Container Events Mixin: readding old event listeners

[abernh]

See https://github.com/Aminerman/vue-kinesis/blob/02eb26ff4fbcd1d646011afa246319d9f1952be9/src/mixins/container_events.js#L49

If I am not mistaken this line should read .removeEventListener

Otherwise the old event gets an additional new event listener added.