Fixed bad assumption about HttpContext

HttpContext is not available when running at console

src/Orchard.Web/Modules/Orchard.ImportExport/Providers/ImportActions/ExecuteRecipeAction.cs

@@ -153,7 +153,9 @@ namespace Orchard.ImportExport.Providers.ImportActions {
             PrepareRecipe(recipeDocument);
 
             // Sets the request timeout to a configurable amount of seconds to give enough time to execute custom recipes.
+            if (_orchardServices.WorkContext.HttpContext != null) {
                 _orchardServices.WorkContext.HttpContext.Server.ScriptTimeout = RecipeExecutionTimeout;
+            }
 
             // Suspend background task execution.
             _sweepGenerator.Terminate();