During an installation of tuleap with an external mysql server, I had a problem with mysql users creation and permission associated.
The mysql users creation is ugly, we should have a look at it and make it better.

Description of the problem:

I have:
- A tuleap server (tuleap_server)
- A remote mysql server (mysql_server)
- A mysql user 'tuleap_root'@'%' with all permissions and grant permissions.

I run the setup.sh with the following options (in addition to the basic ones):
--mysql-host=mysql_server
--mysql-user=tuleap_root
--mysql-user-password=xxxxxx
--mysql-httpd-host=tuleap_server

During the installation a new mysql user 'tuleap_root'@'tuleap_server' is created without grant options. This user is then used instead of the 'tuleap_root'@'%' initially created.

As the created user has no grant permissions we have errors during the setup.sh as we try to give permissions to codendiadm and dbauthuser.