Http specs for linkTo max count deleted events

Fixed up the two linkto maxcount deleted events tests to use the new base spec, and added another (failing) case that uses embed=rich. The other tests pass because they are EmbedLevel.None.

It was just because I was using the Web UI to view the linked stream that I was able to get the error in the first place - since the HTML content type resolves to EmbedLevel.PrettyBody.