you_are_invited_on_dossier -> avis_invitation

- shorter
- clearer

spec/mailers/previews/avis_mailer_preview.rb

@@ -1,8 +1,8 @@
 # Preview all emails at http://localhost:3000/rails/mailers/avis_mailer
 class AvisMailerPreview < ActionMailer::Preview
 
-  def you_are_invited_on_dossier
-    AvisMailer.you_are_invited_on_dossier(Avis.last)
+  def avis_invitation
+    AvisMailer.avis_invitation(Avis.last)
   end
 
 end