Custom Staff Member Fields

[brettshumaker]

We need to find a way to allow users to define their own custom fields. They'll need to be able to define the field name - required, field type (text, text area, ??) - required, html output for the field - optional, and an order value (maybe a drag and drop) - optional. We'll probably want to do some checking against existing field names (including the default fields) so we don't run into any conflicts if a user tries to duplicate a field name. We should generate the template tag to be used for the custom field as well.

Extra credit: allowing a custom field to be applied only to members of a specific group.