feat : add example project for testing plugin.

example/lib/main.dart

@@ -0,0 +1,32 @@
+import 'package:flutter/material.dart';
+import 'package:country_code_picker/country_code_picker.dart';
+
+void main() => runApp(new MyApp());
+
+class MyApp extends StatefulWidget {
+  @override
+  _MyAppState createState() => new _MyAppState();
+}
+
+class _MyAppState extends State<MyApp> {
+  @override
+  void initState() {
+    super.initState();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return new MaterialApp(
+        home: new Scaffold(
+            appBar: new AppBar(
+              title: const Text('CountryPicker Example'),
+            ),
+            body: new Center(
+              child: new CountryCodePicker(
+                  onChanged: print,
+                  // Initial selection and favorite can be one of code ('IT') OR dial_code('+39')
+                  initialSelection: 'IT',
+                  favorite: ['+39', 'FR']),
+            )));
+  }
+}