Using the `_html` suffix in an i18n key is the same as using `html_safe`
on it, which means that translation could potentially be used for XSS
attacks.
allows managers to create users without email
hides email preferences from account page for email-less users
prevents email delivery to users with no email
adds spec for user creation from management
adds specs for user's email requirement
adds spec for no deliveries if no email
