Refactor new Services for thread safety, plus unit tests. Not all services are updated to be correct, only the

ContentService, the rest need to be updated as well.

src/Umbraco.Web/UmbracoModule.cs

@@ -421,13 +421,15 @@ namespace Umbraco.Web
 
 			app.EndRequest += (sender, args) =>
 				{
-					var httpContext = ((HttpApplication)sender).Context;
+					var httpContext = ((HttpApplication)sender).Context;					
 					if (UmbracoContext.Current != null && UmbracoContext.Current.IsFrontEndUmbracoRequest)
 					{
 						//write the trace output for diagnostics at the end of the request
 						httpContext.Trace.Write("UmbracoModule", "Umbraco request completed");	
 						LogHelper.Debug<UmbracoModule>("Total milliseconds for umbraco request to process: " + DateTime.Now.Subtract(UmbracoContext.Current.ObjectCreated).TotalMilliseconds);
-					}					
+					}
+
+					DisposeHttpContextItems(httpContext);
 				};
 		}
 
@@ -438,5 +440,16 @@ namespace Umbraco.Web
 
 		#endregion
 
+		/// <summary>
+		/// Any object that is in the HttpContext.Items collection that is IDisposable will get disposed on the end of the request
+		/// </summary>
+		/// <param name="http"></param>
+		private static void DisposeHttpContextItems(HttpContext http)
+		{
+			foreach(var i in http.Items)
+			{
+				i.DisposeIfDisposable();
+			}
+		}
 	}
 }