fix bug 823: make user-show backward compatible providing 'projects' with the list of project names

fix returned format of authconn get_user_list
Allow partially the old format for adding/removing projects to an user with the array edition

Change-Id: If8741fd8c73fd16222b1236d30fb92f70b673d49
Signed-off-by: tierno <alfonso.tiernosepulveda@telefonica.com>