Remove check of model state in DurationCalculation

We no longer need this check, because it was only relevant with Ember
Data. Additionally it was a cause of a travis-ci/travis-ci#1992, because
of wrong syntax:

    unless someFunction false or true

will only check for a result of someFunction with an argument being the
result of `or` expression.
Don't return finishedAt, startedAt, duration for not started jobs/builds
Fix signing out on failed try to update user data

A while ago I introduced a change to auth code which signs out user on
failed try to get user data. The problem with it was it signed out on
all kind of errors, like network error. I changed the code to log out on
401 status, but I haven't tested it properly, we actually return 403 on
unauthenticated queries for user data.