Be smarter about people entering invalid Facebook usernames
@wjt
Submitted by Will Thompson Link to original bug (#647446)
Description
A user on #empathy today entered some random string as their Facebook username, when they actually didn't have one. It would be nice if, on authentication failure, Empathy would check whether https://facebook.com/<username>
exists; if it's a 404, it could direct the user to https://www.facebook.com/username/.