Google Products feed setup and optimization

16-17     - remove admin login requirement
311-325    - map ViArt SKU to MPN / do not use GTIN
326-337    - added category description to "Product Type"
385-402    - added all images
Google Product feed update

google_product_feed.php - new script for CRON job.
admin_export_google_base.php:
16-17     - re-enable admin security check
132     - bug fix
215-217     - truncate title to 70 chars
316-328     - if empty SKU user a random least repeatable 5 chars as MPN
334     - category order fix