UC-77 Show an email entry box when FB does not supply it

If the user unchecks the 'email' box when registering w/ our Facebook app, we won't get an email address for them from Facebook.  In that case we need to collect it from them before continuing.

https://wikia-inc.atlassian.net/browse/UC-77
Should this be an empty array as opposed to an empty string, for type consistency?