User can be begin without SIRET

app/models/entreprise.rb

@@ -4,4 +4,10 @@ class Entreprise < ActiveRecord::Base
   has_one :rna_information, dependent: :destroy
 
   validates_presence_of :siren
+
+  before_save :default_values
+
+  def default_values
+    self.raison_sociale ||= ''
+  end
 end