mlb: fix event stream subscription params (#643)
mlb: fix event stream subscription params (#643)

Though a series of updated pr's the `plan-format=light` param was lost.
Add it back in.

Fixes: #642
mesosphere/marathon-lb,mesosphere/marathon-lb,vixns/marathon-lb,vixns/marathon-lb,vixns/marathon-lb,mesosphere/marathon-lb