Re-authenticate when oauth token was rejected.

[obilodeau]

OAuth access tokens may be revoked or deleted on the sync server.

When syncing tomdroid with a server that does not accept the access token anymore, Tomdroid should ask the user to re-authenticate and open the browser.

Currently, only an error message is shown when the once valid oauth access token is not accepted anymore by the server.

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Imported from Launchpad using lp2gh.

• date created: 2014-09-26T11:33:08Z
• owner: cweiske
• the launchpad url was https://bugs.launchpad.net/bugs/1374405