AND-3134 

Banner positions change: also relates to AND-3149 an Android native code change so that Banners get positions sent from ads.js in the same way Mpus are sent positions. To achieve this I've added getBannerPosCallback a duplicate of the original getMpuPosCallback function. Also created getBannerPos a duplicate method of getMpuPos. getBannerPosCallback now passes x, y coords, width and height values to native function window.GuardianJSInterface.bannerAdsPosition(x, y, w, h) and now banners are positioned in the same way as MPUs and the original bug 'AND-3134 banner ads alignment incorrect' is now in the correct position.