Fix crash with nil URL.

Author: samvermette

SVWebViewController/SVWebViewController.m

@@ -263,8 +263,8 @@ - (void)stopClicked:(UIBarButtonItem *)sender {
 
 - (void)actionButtonClicked:(id)sender {
     NSArray *activities = @[[SVWebViewControllerActivitySafari new], [SVWebViewControllerActivityChrome new]];
-    
-    UIActivityViewController *activityController = [[UIActivityViewController alloc] initWithActivityItems:@[self.self.webView.request.URL] applicationActivities:activities];
+    NSURL *url = self.webView.request.URL ? self.webView.request.URL : self.URL;
+    UIActivityViewController *activityController = [[UIActivityViewController alloc] initWithActivityItems:@[url] applicationActivities:activities];
     [self presentViewController:activityController animated:YES completion:nil];
 }