public ActionResult Create(FormCollection collection)
 {
     try
     {
         AppWebHelper hlp = new AppWebHelper(
             HttpContext.Request.QueryString[Constants.SPAppWebUrl] as string);
         hlp.AddAdministrator(collection["LoginName"] as string);
         return View("Index", hlp.GetAdministrators());
     }
     catch (Exception ex)
     {
         LogHelper.Log(ex.Message + ex.StackTrace, LogSeverity.Error);
         throw;
     }
 }
        /// <summary>
        /// The RER are a little buggy. Depending on the event triggered, using this:
        /// TokenHelper.CreateAppEventClientContext(properties, true) returns a null appweb although the 
        /// app web exists...Therefore, as I know the name of my App and since the AppWeb's url corresponds to it
        /// I assume that the default appweb location is https://hostweb/appweb. This isn't valid when the App is deployed
        /// trough the AppCatalog. That's why I record the URL of the AppCatalog in case the App gets installed in the
        /// AppCatalog since this info isn't available from CSOM.
        /// </summary>
        /// <param name="properties"></param>
        void AppInstalled(SPRemoteEventProperties properties)
        {
            LogHelper.Log("The application was installed on "+properties.AppEventProperties.HostWebFullUrl);
            using (ClientContext ctx = TokenHelper.CreateAppEventClientContext(properties, false))
            {
                ctx.Load(ctx.Web);
                ctx.Load(ctx.Web.CurrentUser);         
                ctx.ExecuteQuery();
                if(ctx.Web.WebTemplate == Constants.AppCatalogTemplate)
                {
                    LogHelper.Log("Writing app catalog url", LogSeverity.Error);
                    using(StreamWriter sw =  new StreamWriter(HttpContext.Current.Server.MapPath("~/App_Data/AppCataLog.xml")))
                    {
                        sw.Write(ctx.Web.Url);
                    }
                }
                AppWebHelper hlp = new AppWebHelper(properties.AppEventProperties.AppWebFullUrl.AbsoluteUri, true);
                hlp.AddAdministrator(ctx.Web.CurrentUser.LoginName);

            }
        }