SOCIAL_AUTH_GOOGLE_OAUTH2_EXTRA_SCOPE is ignored

[jswain]

The documentation (http://psa.matiasaguirre.net/docs/html/backends/google.html) refers to a parameter, SOCIAL_AUTH_GOOGLE_OAUTH2_EXTRA_SCOPE, that can be set (for example to ['https://mail.google.com'] to extend the default authorisation scope.

SOCIAL_AUTH_GOOGLE_OAUTH2_EXTRA_SCOPE does not appear to be utilised by backend/google.py at all and setting it has no effect on the scope.

Setting SOCIAL_AUTH_GOOGLE_SCOPE = ['https://mail.google.com'] does extend the scope.

[omab]

@jswain, issues fixed. Thanks!