Update jigoshop-admin-reports.php

If $total = 0 Display :
Warning: Division by zero in /home/annon597/public_html/www.themes-wordpress-francais.com/wp-content/plugins/jigoshop/admin/jigoshop-admin-reports.php on line 187
Merge pull request #903 from ThemesWpFr/patch-3

Update jigoshop-admin-reports.php