Replace T4MVC MVC.API call with manual URL construction

WebHandler/ADCompareWebHandler.cs

@@ -4,6 +4,7 @@ using Newtonsoft.Json;
 using System;
 using System.Linq;
 using System.Text;
+using System.Web;
 using System.Web.Mvc;
 
 namespace Disco.Plugins.ADCompare.WebHandler
@@ -82,7 +83,8 @@ namespace Disco.Plugins.ADCompare.WebHandler
 
         private string BuildDashboardHtml()
         {
-            var pluginUrl = Url.Action(MVC.API.Disco.Plugin.PluginWebAction(Manifest.Id, null));
+            // Build the plugin URL manually (T4MVC's MVC.API class isn't available outside the Disco solution)
+            var pluginUrl = "/Plugin/" + HttpUtility.UrlEncode(Manifest.Id);
 
             return @"
 <div id='adcompare'>