Tableview is freezing with server based images.

[wanglouin1990925]

[liufengting]

@wanglouin1990925 Hi, get image size method is 'NSURLConnection.sendSynchronousRequest(request as URLRequest, returning: nil)' in FTImageSize.swift, It's a synchronous method. It blocks main thread when cannot connect to server. I don't have simple solutions, maybe you could set image size to a certain value.