add db/import functionality to ecommerce module

[ischommer]

http://open.silverstripe.com/browser/modules/sapphire/trunk/core/model/DatabaseAdmin.php#L268 DatabaseAdmin?.php:258 function import()

references ecommerce-specific code (classes Product and ProductGroup?). it reads an arbitrary file from the server specified via GET, doesn't check for ADMIN-permissions (as far as i can tell), and doesn't validate the filename, which means its a directory traversal risk.

i've removed this code from core and attached it here, in case you want to add it to the ecommerce module.

its also a good base for a generic importer module (perhaps in GenericDataAdmin?).

[sminnee]

Not required for 0.6. Please minimise the number of tickets in 0.6