Don't emit an empty player status.

[STRML]

This can be potentially confusing for client applications and crashes the example code.

Sometimes, when streaming to a warm device, I'll see this MEDIA_STATUS message come down:

{ type: 'MEDIA_STATUS', status: [], requestId: 0 }

media.js then tries to pull out data.status[0] and emits a 'status' event with an undefined payload.

This small patch simply holds off on emitting until there's actually data to emit, so users don't have to nullcheck on 'status' events.

[thibauts]

Awesome :) thanks