Adding an option to install without mysql root user

Change-Id: I4eda669aa15ed237e30c0e2dd17f5a29b1475730
Merge commit 'refs/changes/55/2855/2' of ssh://gerrit.tuleap.net:29418/tuleap into stable

* ssh://gerrit.tuleap.net:29418/tuleap:
  Adding an option to install without mysql root user
This is Tuleap 7.3.99.53

Change-Id: I7158fe98a05fc65d638d52a4faf4f14cf86612c5