add single_conversation example

example/lib/single_conversation.dart

@@ -0,0 +1,74 @@
+import 'package:flutter/material.dart';
+import 'package:stream_chat_flutter/stream_chat_flutter.dart';
+
+void main() {
+  final client = Client('qk4nn7rpcn75');
+  runApp(StreamChat(
+    client: client,
+    child: MyApp(),
+  ));
+}
+
+class MyApp extends StatefulWidget {
+  @override
+  _MyAppState createState() => _MyAppState();
+}
+
+class _MyAppState extends State<MyApp> {
+  ChannelClient _channelClient;
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Flutter Demo',
+      theme: ThemeData(
+        primarySwatch: Colors.blue,
+      ),
+      home: ChannelPage(_channelClient),
+    );
+  }
+
+  @override
+  void initState() {
+    super.initState();
+
+    final streamChat = StreamChat.of(context);
+    _channelClient = streamChat.client.channel('messaging', id: 'godevs');
+
+    streamChat
+        .setUser(
+      User(id: "wild-breeze-7"),
+      'eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ1c2VyX2lkIjoid2lsZC1icmVlemUtNyJ9.VM2EX1EXOfgqa-bTH_3JzeY0T99ngWzWahSauP3dBMo',
+    )
+        .then((_) {
+      _channelClient.watch();
+    });
+  }
+
+  @override
+  void dispose() {
+    StreamChat.of(context).dispose();
+    super.dispose();
+  }
+}
+
+class ChannelPage extends StatelessWidget {
+  ChannelPage(this.channelClient);
+
+  final ChannelClient channelClient;
+
+  @override
+  Widget build(BuildContext context) {
+    return StreamChannel(
+      channelClient: channelClient,
+      child: Scaffold(
+        body: Column(
+          children: <Widget>[
+            Expanded(child: MessageListView()),
+            MessageInput(),
+          ],
+        ),
+      ),
+    );
+  }
+}