- fix link bot for Test Envinroment

- If invite not exist, error message
- Username (where name and surname don't exists).

emails/admin/registration/enUs/html.pug

@@ -1,4 +1,4 @@
-p #{name} #{surname} has just registered on #{nomeapp}
+p #{username} (#{name} #{surname}) has just registered on #{nomeapp}
 p With the following access datao:
 span Username: 
     strong  #{username}<br>