WIP oauthclient/accounts: permanent login support

* Sets session.permanent when then user marks 'remember me'.

* Allows configuration of oauth login to set if session should
  be permanent.

Signed-off-by: Javier Martin Montull <javier.martin.montull@cern.ch>
Yes. Plus it would be nice to add argument to callback url that overrides the default value from the `OAUTHCLIENT_SESSION_PERMANENT_LOGIN`.