Bug 17669: Incorporate the changes in cleanup_database

Bug 17669: Incorporate the changes in cleanup_database

Two command line options are added:
[1] -temp-uploads to indicate that you want to purge these uploads,
[2] -temp-uploads-override DAYS to (optionally) tell that you want to
    override the corresponding pref value.

Test plan:
[1] Check the modified usage statement.
[2] If needed, backup your temporary uploads :)
    In case you do not have one, add a temporary one with Tools/Upload.
    Note: Do not choose an upload category.
[3] Set pref to 0, and run cleanup_database with only --temp-uploads.
    No files should be deleted.
[4] Check number of "old" temp uploads. Set pref to nonzero value.
    Verify that the oldest are gone (depending on the value chosen).
[5] Set pref to 0 again.
    If all uploads are gone now, add a new one with Tools/Upload.
    Run cleanup_database with --temp-uploads --temp-uploads-override -1
    All temporary files are gone.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Mirko Tietgen <mirko@abunchofthings.net>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>