Fixing initial setup screen

Setup module hardcoded descriptor needs Location pointing to ~/Themes

--HG--
branch : perf

src/Orchard.Web/Modules/Orchard.Setup/SetupMode.cs

@@ -105,6 +105,7 @@ namespace Orchard.Setup {
             private readonly ExtensionDescriptor _theme = new ExtensionDescriptor {
                 Name = "SafeMode",
                 DisplayName = "SafeMode",
+                Location = "~/Themes",
             };
 
             public ExtensionDescriptor GetRequestTheme(RequestContext requestContext) { return _theme; }