open Safari app in response to JS window open, target = _blank tag

WKWebView_open_new_window.swift

// confirm : WKUIDelgate protocol
    
    // To dealt with JS window open or target = _blank tag
    // - result : open Safari app
    func webView(webView: WKWebView, createWebViewWithConfiguration configuration: WKWebViewConfiguration, forNavigationAction navigationAction: WKNavigationAction, windowFeatures: WKWindowFeatures) -> WKWebView? {
        
        if UIApplication.sharedApplication().canOpenURL(navigationAction.request.URL!) {
            UIApplication.sharedApplication().openURL(navigationAction.request.URL!)
        }
        
        return nil
    }