Fix for: user creation should add a unique numeric identifier to the user.

See:
https://github.com/georchestra/georchestra/issues/573
Add unique number when creating groups.  default is ou

See https://github.com/georchestra/georchestra/issues/614
Merge pull request #618 from jesseeichar/addUniqueNumbericValueForUser_573

Fix for: user creation should add a unique numeric identifier to the user