Fix exception in clusters/applications_controller.rb

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/controllers/projects/clusters/applications_controller.rb

@@ -7,7 +7,7 @@ class Projects::Clusters::ApplicationsController < Projects::ApplicationControll
   def create
     application = @application_class.find_or_initialize_by(cluster: @cluster)
 
-    if has_attribute?(:hostname)
+    if application.has_attribute?(:hostname)
       application.hostname = params[:hostname]
     end