Gets virtual page routing working, now just need to document.

src/Umbraco.Web.Common/Controllers/IVirtualPageController.cs

@@ -0,0 +1,15 @@
+using Umbraco.Core.Models.PublishedContent;
+
+namespace Umbraco.Web.Common.Controllers
+{
+    /// <summary>
+    /// Used for custom routed controllers to execute within the context of Umbraco
+    /// </summary>
+    public interface IVirtualPageController
+    {
+        /// <summary>
+        /// Returns the <see cref="IPublishedContent"/> to use as the current page for the request
+        /// </summary>
+        IPublishedContent FindContent();
+    }
+}