add prompt confirmation and update carton

lib/pages/contact/contact_editor.dart

@@ -29,17 +29,21 @@ class _ContactEditorState extends State<ContactEditor> {
   TextEditingController _facebook = new TextEditingController();
 
   bool _isLoading = false;
+  bool isNew;
 
   @override
   void initState() {
     super.initState();
     if (widget.contact != null) {
+      isNew = false;
       _usaPhone.text = widget.contact.usaContactNumber;
       _mmPhone.text = widget.contact.mmContactNumber;
       _usaAddress.text = widget.contact.usaAddress;
       _mmAddress.text = widget.contact.mmAddress;
       _email.text = widget.contact.emailAddress;
       _facebook.text = widget.contact.facebookLink;
+    } else {
+      isNew = true;
     }
   }
 
@@ -83,9 +87,7 @@ class _ContactEditorState extends State<ContactEditor> {
               leading: new IconButton(
                   icon: new Icon(CupertinoIcons.back, color: primaryColor),
                   onPressed: () {
-                    showConfirmDialog(context, "back.button_confirm", () {
-                      Navigator.of(context).pop();
-                    });
+                    Navigator.of(context).pop();
                   }),
               shadowColor: Colors.transparent,
               backgroundColor: Colors.white,