chore(build): remove definitively conversation module and replace it by mails module

Author: thegdznet

src/app/override/modules.ts

@@ -2,10 +2,10 @@ export default [
   require('~/framework/modules/blog'),
   require('~/framework/modules/collaborativewall'),
   require('~/framework/modules/connectors/lvs'),
-  require('~/framework/modules/conversation'),
   require('~/framework/modules/form'),
   require('~/framework/modules/homework'),
   require('~/framework/modules/homework-assistance'),
+  require('~/framework/modules/mails'),
   require('~/framework/modules/mediacentre'),
   require('~/framework/modules/news'),
   require('~/framework/modules/pronote'),