Also do not send change to MH if deletion is not done

I put a for loop over the list to generate a foreign key for each item in the list.

=> a type can have multiple superiors (only instance of LeObject can have one)

Conflicts:
	EditorialModel/model.py
	EditorialModel/test/me.json

Add the possibility to change the migartion handler of a Model
It will send changes one by one to the new migartion handler
so it can re-create the Editorial Model

 use it to re-run ME creation in a new Migration Handler