Update statusBar.js

Since only iOS uses translucent statusbar, it's possible to test against iOS version 4-8 to date. This version has 20px status bar height baked in, because there's no reason to calculate it on-the-fly – there's either no pushing down or there's 20px push down.

Usage: Use html conditional class to add padding to any element required.

Note: iOS 4 requires classList API polyfill.