[READY] Browsers compatibility

We now have a fully covered unit testing for:

- Safari 6 (OS X)
- Mobile Safari (iOS 5.1)
- Android Stock Browser (Android 4.0)
- Firefox 21 (Windows 7)
- Internet Explorer 8 (Windows 7)

This is the result of the following PR:

- [x] #70 Sauce Remote Testing
- [x] #72 Gecko Compatibility
- [x] #73 Internet Explorer 8 Features Compatibility
- [x] #74 IE8 Compatible Unit Testing

They have been merged in the `browsers-compatibility` branch first.  
Secured data are not pushed in PR incoming from forks.

If the Travis badge is failing for this PR, consider this build as a reference:

> https://travis-ci.org/BBC-News/Imager.js/builds/17475266

![](http://i.imgur.com/qD9FjHh.gif)