Fix on the call to FieldDataHandler.from_name

lodel/editorial_model/components.py

     def __init__(self, uid, data_handler, display_name = None, help_text = None, group = None, **handler_kwargs):
         super().__init__(uid, display_name, help_text, group)
         self.data_handler_name = data_handler
-        self.data_handler_cls = FieldDataHandler(data_handler)
+        self.data_handler_cls = FieldDataHandler.from_name(data_handler)
         self.data_handler_options = handler_kwargs
         self.data_handler_instance = self.data_handler_cls(**handler_kwargs)
         ## @brief Stores the emclass that contains this field (set by EmClass.add_field() method)

lodel/leapi/datahandlers/field_data_handler.py

     # @param fieldtype_name str : a field type name
     # @return a string representing a python module name
     @staticmethod
-    def module_name(self, fieldtype_name):
+    def module_name(cls, fieldtype_name):
         return 'leapi.datahandlers.data_fields.%s' % fieldtype_name
 
     ## @brief __hash__ implementation for fieldtypes