Mutating webhook for client IDs

[dmolik]

when registering a client to use a stream a client needs to provide a unique ID to poll for streams, frequently the POD hostname will be used or even the client's IP address. This can cause an ever growing list of stale stream client IDs on the server. Determine if it's possible to create a semi-declaritive or atleast deterministic way to have a pool of IDs per client group and assign them out via a Mutating Webhook.