Email Dashboard Widget: allow for "primary" address

Allow the email dashboard widget to configure an email type to be used as a "primary" type of which there can be only one. Allow the end-user to mark an address as this type at both the point of creation and from the drop-down editing buttons. The front-end of the widget should clearly mark the selected email address of this type. The backend must allow for only one address of this type.

For practical purposes, the type configured may be an extended email address type that could be unique to COmanage Registry. The type can be used in the Elector Data Filter to pick out the single email address that a user has marked as their primary address for use in downstream provisioning.