title: get google oauth refresh token after first login
body: <p>I have implemented a google oauth signup.
  I can request the tokens with the code provided when the user clicks login via google.</p>
  <p>However, the tokens only include the refresh token the very first time that the user signs up/logs in.
  All later attempts to get tokens with the auth code only return an access token, but not a refresh token.
  I have to manually revoke the app permission in the user's google settings in order to force a new permission prompt which provides me with a new refresh token.</p>
  <p>Is there some way to request a refresh token with the auth code? I.e. not just during the first login.</p>