Treat http statuses >=400 as connection errors rather than auth errors

[jrichter1]

Trying to log in started failing with the 'invalid account information' message, yet it was caused by the server returning 500 (internal server error).
Would it make more sense to treat such responses as connection errors and leave the authentication error handling solely for 401 responses?

@dgolovin WDYT?

[dgolovin]

The reason is my changes in request service, the fix is here #1264, but some test issues still have to be fixed.