Updating exchange token to user new 'expires' value instead of 'expires_in'

[ghost]

I can't seem to find any reason as to why the response return 'expires' as the documentation talks about 'expires_in', but this was required to get the long lived tokens working.
see: https://developers.facebook.com/docs/facebook-login/access-tokens#apptokens

[huandu]

It was expires. It seems facebook changes the field name in response. Maybe we need to use expires_in by default and use expires as fallback.

[huandu]

I fix it in 3c4ba14. Close this merge request as it's not a clean fix.

[ghost]

Thanks, this is a good solution. Perhaps there are still multiple version of the code at different versions deployed.