Add Event to api types

In the spirit of HATEOAS, I think when we present this information in an HTTP response it should be in the form of two self-links:
```json
{
"OriginalSelfLink" : "/api/${APIVERSION}/${KIND}/?uid=${UID}&version=${VERSION}",
"LatestSelfLink" : "/api/${APIVERSION}/${KIND}/${NAME}"
}
```
Of course, since we don't support these URLs yet, I don't expect you to do it in this PR.