gcontacts: refresh access_tokens when a 401 is received
gcontacts: refresh access_tokens when a 401 is received

https://developers.google.com/api-client-library/python/guide/aaa_oauth
talks about refresh and access tokens, it seems the old code only worked
with access tokens, while the new one tries to get a new access token
based on the refresh one first -> less likely that we need to ask the
user to confirm something in the browser.

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