Option for tray icon to display user status

Cleaned up version of original PR https://github.com/tux3/qTox/pull/863

Setting added for tray icon to be displayed as user status. Default value is off (original tox icon as it is now). Useful when user wants to see his current status in tray. Especially handy when auto-away kicks in, we immediately can see if we are away or not without a risk of breaking away status.