Fix sla #3150 - Tuleap uses LDAP uid to interact with gerrit users

We need to use LDAP uid (login) instead of id (internal value of LDAP) for
user management between Tuleap and Gerrit.

Change-Id: Ic1226200f9de2111acec159e81bd8b2bf0321029
Merge commit 'refs/changes/06/406/3' of http://gerrit.tuleap.net/tuleap into tuleap-stable-master

* http://gerrit.tuleap.net/tuleap:
  Fix sla #3150 - Tuleap uses LDAP uid to interact with gerrit users
Tuleap 5.12.99.58