do not prevent login on missing google profile info

The documentation[1] does not seem to mention it, but at least given_name and
family_name are sometimes not supplied by the userinfo endpoint.

[1] https://developers.google.com/accounts/docs/OAuth2Login#userinfocall
Merge pull request #185 from chazmcgarvey/google-optional-userinfo

do not prevent login on missing google profile info