Added custom dialog.

lib/ui/dialog.dart

@@ -0,0 +1,20 @@
+import 'package:flutter/material.dart';
+
+var baseDialogTheme = DialogTheme(
+  backgroundColor: Colors.green[100],
+  elevation: 40.0,
+  shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(15.0)),
+);
+
+AlertDialog Function(BuildContext) errorDialogBuilder(String title, String message) {
+  return (BuildContext context) =>
+      AlertDialog(title: Text(title), content: Text(message), actions: <Widget>[
+        RaisedButton(
+          onPressed: () => Navigator.of(context).pop(),
+          child: Text(
+            "Dismiss",
+            style: TextStyle(fontWeight: FontWeight.bold, color: Colors.black),
+          ),
+        )
+      ]);
+}