Rename ConnectorUnit.model_name to for_model_name
Rename ConnectorUnit.model_name to for_model_name

Because 'model_name' contains the name of the model we are working in in the
ConnectorEnvironment, and this 'model_name' represents the list of models on
which a ConnectorUnit can be used.

This is too confusing, especially since ConnectorUnit.model_name is hardly used

leorochael/queue