Added Systems Save to Settings

The systems list will now be saved to settings after a scan and reloaded
on next load of psf.
Fixed Add Repository Cancel InvalidURL Bug

This fixes the bug that wouldn't allow you to cancel if you had an
invalid url in the Add Repository form.
Added Option to Save or not Save Systems

Added an option to settings that would allow the user to specify if they
want to save the settings or not.
Fixed Tooltip on Settings Option
Save Systems on Exit