Gets data about where the user is looking, passes it to the optional callback function (if provided), and returns it.
Parameter:
callback(function): (OPTIONAL) A callback function to execute. It will be passed an object with the following attributes automatically:pan(number): The pan (ie, left or right shift) of where the user is facing in the current spheretilt(number): The tilt (ie, up or down shift) of where the user is facing in the current sphere
Returns: A promise that resolves to the same object that is passed to the callback.