Do proper initialization of _fetchJobInProgress.

That confused win32, since this flag was true very often.
Use the mirall config file for all Keychain jobs.

Also set the job as parent to get proper deletion of the
settings object.
Add method clearCookieJar which wipes QNAMs cookies.
Remove a superflous MessageBox. User is asked for Password instead.
Make the CheckServerJob ignoring credential fails.
Do not wipe the credentials from config for reconnect.

This should fix bug #1491