Connection established/lost notification should be based on is_online property

[Roman Yepishev]

At the moment the notification about connection success is sent immediately after syncdaemon notifies about SYS_CONNECTION_MADE, which is before the authentication takes place leading to the following message to the user:
http://ubuntuone.com/p/fIP/

StatusChanged signal is sent with is_online field which should probably checked and notification about connect/disconnect should be based on this field. is_online is True when it's in QUEUE_MANAGER state.