Fix "your system is up to date" message on panel and also on main window of update manager

[wpshooter]

Please consider fixing the "your system is up to date" message(s) that are displayed on both the panel icon and also on the main window of update manager so that it does not give FALSE message that your system is up to date to Linux Mint mate users who choose to NOT have the update manager preferences set to do automatic polling and retrieval and application of updates but instead want to do their updating on a manual/dedicated basis.

As it stands now the messages that are being issued in these places FALSELY displays a message reporting that the system is up to date, when in fact it MAY NOT be if the user has chosen to disable automated updating.

I.E. - need to have two different messaging displays depending on if the Linux Mint user is choosing to have these task performed on an automated basis or to have these task done on a manual/dedicated basis.

Thanks.