Mostly about the changes on types hierarchy

Added Lodel/settings/migrations.py that I forget
Disabled the --merge option that was given to the makemigrations command by the MH

On se base sur gettext, mais avec l'utilisation d'une langue par défaut qui sera obligatoire lors de la création de la chaine.

Behaviour changed for EmComponent and childs create method :
	- Takes care of duplicated names at creation
	- Handle all the checks in EmComponent method
Factorization of EmField.get_class_table() method
Added a @property method class_table_name to EmClass

Now an MlString instance is able to say if another MlString instance is equivalent using mlstr1 == mlstr2

Created the class Lodel.utils.mlstring.MlString needed by EditorialModel.lib.component.EmComponent
The first test pass ! =)

Lodel/sttings/__init__.py wasn't able to import files when called by manage.py
Renaming em to EditorialModel and moved Em* objects to EditorialModel/lib
Adding a first test (that do not pass because of syntax errors in Em* classes)