Bug 11509: improve usage information printed by koha-create

Bug 11509: improve usage information printed by koha-create

This patch makes koha-create print better and more descriptive usage
information. Also adds the --help and -h switches.

Sponsored-by: Universidad Nacional de Cordoba
Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Removed trailing " from:
  $scriptname [db usage mode] [options] instancename"

Signed-off-by: Galen Charlton <gmc@esilibrary.com>