G+: use access_type=offline and approval_prompt=force so we can get refresh tokens
G+: use access_type=offline and approval_prompt=force so we can get refresh tokens

details: http://googleappsdeveloper.blogspot.com.au/2011/10/upcoming-changes-to-oauth-20-endpoint.html

kylewm/oauth-dropins,snarfed/oauth-dropins,snarfed/oauth-dropins,snarfed/oauth-dropins