connectionError() should not bring LoginDialog

[KitsuneRal]

We should only show a login dialog in cases when we're certain there's a problem with access_token. Right now it is shown on any error from PasswordLogin job, which in turn is invoked every time when SyncJob has problems (by means of Connection::reconnect()).

Speaking of Connection::reconnect(), I wonder if it even should exist in its current form. Storing a password even in memory is not a very good thing. The protocol mandates usage of refresh_tokens to get a new access_token - probably that's what is supposed to be in there. And even that should only be used in case when access_token becomes invalid, not for all cases of access denial.