When creating user, infer email from name

[Brian Lewis]

Mainly a UI simplification:

if the user name is an email, this is an "Identity" account, and the email is the smae as the user name.

If the user name is not an email, then the record represents an Active Directory group. An email is required: so set it to

<name>@<context>.org

e.g. [e-mail]

No emails will ever get sent to his address.

[Brian Lewis]

Pull Request #275 closes