Fix bug in the update of records with custom primary_keys

The previous code would result in this error:
NoMethodError Exception: undefined method `find_all_by_id' for #<Class...

lib/netzke/basepack/data_adapters/active_record_adapter.rb

@@ -130,7 +130,7 @@ def destroy(ids)
     end
 
     def find_record(id)
-      @model_class.find_all_by_id(id).first
+      @model_class.where(@model_class.primary_key => id).first
     end
 
     # Build a hash of foreign keys and the associated model