12298: Prevent duplicate users with gmail openid.

I'm not sure why this is happening, but we can work around it by using
the email to lookup the UserProfile object instead of the openid key.
12298: log error when we apply our gmail OpenID hack

Hopefully this will give us enough info to understand the issue better
and maybe make a better fix.
Merge pull request #89 from bendk/gmailopenid

12298: Gmailopenid