fix(userEP): Use mail attribute instead of tuple of uid and mail

This bug was introduced in #14 by changing the signature of the called method.

mail_alias_creator/entry_processors/user.py

@@ -29,7 +29,7 @@ def process(self, alias_address_provider):
         """Process."""
         logger.debug("Processing user EP with {}".format(self.user))
         from ..main import LDAP
-        mail = LDAP.get_user_primary_mails([self.user])[0]
+        mail = LDAP.get_user_primary_mails([self.user])[0][1]
         if mail is None:
             logger.error("User {} does not exist or has no primary mail.".format(self.user))
             if CONFIG["main"].getboolean("strict"):