Support Facebook Login without email

[puilp0502]

Addresses #623.

I didn't know if I should bump up the version, so I left it as it is.

[samtstern]

@puilp0502 just wanted to say I know this is lingering, I have been caught up on some other stuff and will test this soon. Thank you for doing it!

[samtstern]

@puilp0502 FYI I changed the target branch to version-2.0.0-dev as that's where the next version will come from. You may have to change your local setup a bit, let me know if that's confusing.

[samtstern]

Ok I just went and got a new phone number (thanks Google Voice) and then made a Facebook account that has no email. Then I signed in and got the following (see below).

I am surprised that signing in like that even works! I guess email is not a hard requirement for Facebook accounts (learn something new about your own products every day haha).

I am fine to merge this change, but @amandle can you chime in and let me know if this could cause any potential problems?

Console:

App:

[amandle]

LGTM, Twitter also doesn't require email be shared, so I don't foresee this change causing problems