Added test to verify image view can cancel and restart the same request.
Added test to verify image view can cancel and restart the same request.

sessuru/AlamofireImage,easyui/AlamofireImage,Pluto-tv/AlamofireImage,easyui/AlamofireImage,Baza207/AlamofireImage,Pluto-tv/AlamofireImage,daniele-pizziconi/AlamofireImage,Baza207/AlamofireImage,sessuru/AlamofireImage,Alamofire/AlamofireImage,Alamofire/AlamofireImage,daniele-pizziconi/AlamofireImage