Events should have UUIDs #1751
Description
Right now, an event's id field is essentially its type plus a hash of its data, e.g. DNS_NAME:1e57014aa7b0715bca68e4f597204fc4e1e851fc. This is useful but causes problems when you need to look up a very specific event, and there are multiple with the same ID. Every event should have its own universally unique ID.