Use resize events as proxy for orientation change

Crosswalk doesn't return a usable value for window.orientation
on Android, which the app was previously relying on to determine
portrait/landscape.

It also seems as though Crosswalk Android isn't firing
orientationchange events, even though "onorientationchange" is
present in the window object.

Consequently, orientation changes weren't being detected.

By forcing fallback to resize events, and comparing window
height/width, we "simulate" orientationchange events to work around
these issues.

Fixes #2