As an administrator I would like to invite a user with its email only (Shibboleth)

When inviting users, administrators have to enter unique username/email (unicity is required now). Username is optional For a Shibboleth authentication: If a user is invited with its email only, the shibboleth invitation plugin is going to create the Nuxeo user with email as username and set the ACLs on the target document. Then, waiting for authentication, the plugin is going to update those ACLs and this Nuxeo user according to the information returned by Shibboleth server (real username and email).