Removed undefined method exception

Fixes the following error exception when adding the flash notifications package in laravel 5.2:

    [RuntimeException]                                                                                                                                                     
    Error Output: PHP Fatal error:  Call to undefined method Illuminate\Foundation\Application::bindShared() in /var/www/html/laravel-app/vendor/srmklive/flash-notifications/src/FlashAlertServiceProvider.php on line 61

src/FlashAlertServiceProvider.php

@@ -58,7 +58,7 @@ private function registerFlashAlert()
             'Srmklive\FlashAlert\FlashAlertSessionStore'
         );
 
-        $this->app->bindShared('flashalert', function() {
+        $this->app->singleton('flashalert', function() {
             return $this->app->make('Srmklive\FlashAlert\FlashAlertHandler');
         });
     }