Update test to use instance events streaming route
Update test to use instance events streaming route

* With #14, TPS watcher no longer uses the deprecated
`SubscribeToEvents` in favor of the `SubscribeToInstanceEvents` API.  The
mocked out api endpoint needed to be updated as well

Authored-by: Seth Boyles <21277fcf6b37bdc0fc86af5805d434d3cee634ae@pivotal.io>

cloudfoundry-incubator/tps