Starts observing for different data types and stream it to iOS companion app
func startStream(forDataTypes dTypes: Set<ReadTypes>, completion: @escaping(Bool, TerraWatchOSError?) -> Void)
dTypes: Set<ReadTypes -> A set of all the types to start observing for
completion: @escaping(Bool, TerraWatchOSError?) -> Void -> A completion signifying if the stream has started successfully or not