updates unit test to ensure UmbracoContext.Current is nulled, updates dispose on application context to

not dispose the database if it is not configured.

src/Umbraco.Core/ApplicationContext.cs

@@ -256,7 +256,7 @@ namespace Umbraco.Core
                 this.ApplicationCache = null;
                 if (_databaseContext != null) //need to check the internal field here
                 {
-                    if (DatabaseContext.Database != null)
+                    if (DatabaseContext.IsDatabaseConfigured)
                     {
                         DatabaseContext.Database.Dispose();       
                     }                    

src/Umbraco.Core/Sync/DefaultServerMessenger.cs

@@ -234,6 +234,10 @@ namespace Umbraco.Core.Sync
         {
             if (refresher == null) throw new ArgumentNullException("refresher");
 
+            LogHelper.Debug<DefaultServerMessenger>("Invoking refresher {0} on single server instance, message type {1}",
+                                                    () => refresher.GetType(),
+                                                    () => dispatchType);
+
             //if it is a refresh all we'll do it here since ids will be null or empty
             if (dispatchType == MessageType.RefreshAll)
             {

src/Umbraco.Tests/TestHelpers/BaseDatabaseFactoryTest.cs

@@ -282,7 +282,7 @@ namespace Umbraco.Tests.TestHelpers
 		    get { return ApplicationContext.DatabaseContext; }
 	    }
 
-        protected UmbracoContext GetUmbracoContext(string url, int templateId, RouteData routeData = null)
+        protected UmbracoContext GetUmbracoContext(string url, int templateId, RouteData routeData = null, bool setSingleton = false)
         {
             var cache = new PublishedContentCache();
 
@@ -300,6 +300,11 @@ namespace Umbraco.Tests.TestHelpers
                 ApplicationContext,
                 new PublishedCaches(cache, new PublishedMediaCache()));
 
+            if (setSingleton)
+            {
+                UmbracoContext.Current = ctx;
+            }
+
             return ctx;
         }
 

src/Umbraco.Tests/TestHelpers/BaseUmbracoApplicationTest.cs

@@ -2,6 +2,7 @@
 using Umbraco.Core;
 using Umbraco.Core.Configuration;
 using Umbraco.Core.ObjectResolution;
+using Umbraco.Web;
 
 namespace Umbraco.Tests.TestHelpers
 {
@@ -27,7 +28,7 @@ namespace Umbraco.Tests.TestHelpers
         {
             //reset settings
             SettingsForTests.Reset();
-
+            UmbracoContext.Current = null;
             TestHelper.CleanContentDirectories();
             //reset the app context, this should reset most things that require resetting like ALL resolvers
             ApplicationContext.Current.DisposeIfDisposable();