Update tests/TestCase.php to laravel 5.1

http://laravel.com/docs/5.1/upgrade#upgrade-5.1.0

Author: danny50610

tests/TestCase.php

@@ -2,6 +2,13 @@
 
 class TestCase extends Illuminate\Foundation\Testing\TestCase {
 
+    /**
+     * The base URL to use while testing the application.
+     *
+     * @var string
+     */
+    protected $baseUrl = 'http://localhost';
+
     /**
      * Creates the application.
      *