[SlimDevices: Beta] Add time finished to Music Library Scan status report

[Greg Klanderman]

Speaking of scanning, since there's now a separate scan log file, is
there any option to have it create a new log file for each scan rather
than appending?  Maybe add a date/time stamp to the filename?  When I
have the debugging on I'd prefer to have a separate log file per scan
because otherwise when searching I invariably end up in the wrong
scan's debug output.

greg