added AppBar for logout

src/dashboard/lib/graphing/communitygraph.dart

 import 'package:circlegraph/circlegraph.dart';
 import 'package:dashboard/querying/datagetter.dart';
+import 'package:dashboard/ui/util/logged_in_appbar.dart';
 import 'package:enhanced_future_builder/enhanced_future_builder.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
@@ -102,6 +103,7 @@ class CommunityGraphViewPage extends StatelessWidget {
 
   Widget build(BuildContext context) {
     return Scaffold(
+        appBar: LoggedInAppBar(),
         backgroundColor: Colors.white,
         floatingActionButton: FloatingActionButton(
           onPressed: () => redirectToCommunityMetaGraph(context),

src/dashboard/lib/main.dart

 import 'package:dashboard/exceptions/login_exception.dart';
 import 'package:dashboard/graphing/communitygraph.dart';
 import 'package:dashboard/loading.dart';
-import 'package:dashboard/sign_in/loginpage.dart';
+import 'package:dashboard/ui/sign_in/loginpage.dart';
 import 'package:dashboard/util/loginhelper.dart';
 import 'package:dashboard/util/user.dart';
 import 'package:enhanced_future_builder/enhanced_future_builder.dart';

src/dashboard/lib/sign_in/loginpage.dart → src/dashboard/lib/ui/sign_in/loginpage.dart

 import 'package:dashboard/exceptions/login_exception.dart';
 import 'package:dashboard/main.dart';
-import 'package:dashboard/sign_in/login_form.dart';
+import 'package:dashboard/ui/sign_in/login_form.dart';
 import 'package:dashboard/util/loginhelper.dart';
 import 'package:dashboard/util/user.dart';
 import 'package:flutter/cupertino.dart';

src/dashboard/lib/ui/util/logged_in_appbar.dart

+import 'package:dashboard/main.dart';
+import 'package:dashboard/util/loginhelper.dart';
+import 'package:flutter/material.dart';
+
+class LoggedInAppBar extends PreferredSize {
+  @override
+  Size get preferredSize => Size.fromHeight(60);
+
+  Future<void> _onLogout(context) async {
+    await LoginHelper().logout();
+    Navigator.of(context).pushReplacement(
+      MaterialPageRoute(
+        builder: (context) => MyApp(),
+      ),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return AppBar(
+      backgroundColor: Colors.blue,
+      actions: [
+        Padding(
+          padding: const EdgeInsets.all(8.0),
+          child: TextButton.icon(
+            onPressed: () => _onLogout(context),
+            icon: Icon(
+              Icons.logout,
+              color: Colors.white,
+              size: 25,
+            ),
+            label: Text(
+              "Logout",
+              style: TextStyle(
+                color: Colors.white,
+                fontSize: 20,
+              ),
+            ),
+          ),
+        ),
+      ],
+    );
+  }
+}