Use the Email registration module by default

Usernames are not user-friendly.

1. Why make users think up a username when they can use an email address.
2. Why display ugly usernames when we could just use people's real names.

• Install the email_registration module as part of the Zephyr profile.
• Adds a field to the Drupal user entity to store a user's real name.
• Use the zephyr_user_user_format_name_alter so the user's real name is user where the username was previously.