upgrade before_filter to new syntax

app/controllers/concerns/has_filters.rb

@@ -3,7 +3,7 @@ module HasFilters
 
   class_methods do
     def has_filters(valid_filters, *args)
-      before_filter(*args) do
+      before_action(*args) do
         @valid_filters = valid_filters
         @current_filter = params[:filter]
         @current_filter = @valid_filters.first unless @valid_filters.include?(@current_filter)