适配iOS11问题:如果有用到ESPictureView的_offsetY，可能产生的问题

[faxianlei]

    if (@available(iOS 11.0, *)) {
        if ([self respondsToSelector:@selector(setContentInsetAdjustmentBehavior:)]) {
            self.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;
        }
    }