Updating Google OpenID, OAuth and OAuth2 documentation links.
Merge pull request #589 from JasonSanford/master

Update Google OpenID, OAuth and OAuth2 documentaion links
Add option to use email address as username. Closes #597
Merge branch 'master' of github.com:omab/django-social-auth
v0.7.19
Convert access_token into a Token instance on OAuth backends
v0.7.20
Merge remote-tracking branch 'upstream/master'