remove unnecessary host and port parsing

These are not really needed separately as getAppState will provide the media channel URL when the application is launched when needed.
add simple private mechanism to wipe state
have launchApp trigger heartbeat

Instead of having the heartbeat call itself, just have launchApp do it once.
poll state on launch when using message channel

When the application transitions from starting to launching and a message channel is requested, the app state will squirrel away the WebSocket URL in the additionalData field.

The first step of many, the Message Channel is not yet created, just the URL found.
add an empty MessageChannel object