Add support for Qt 5.4 WebEngine

I've implemented a simple wrapper around the webengine initialization function call to be able to use QtWebEngine QML modules too in go-qml applications. I've placed it in a separate folder so that only people needing it will have to have the Qt 5.4 dependencies installed. I've also added a simple example loading the CodinGame website which is very heavy on animation (hence why webkit fails utterly with it).