Fixed SSE event name regression

The SSE event name should be prefixed with the event: tag, not name:,
according to http://www.w3.org/TR/2009/WD-eventsource-20091029/.

This is a regression just on master, the code is fine on 2.2.x and
earlier.
Merge pull request #2224 from jroper/sse-event-name

Fixed SSE event name regression