Adding ability to search by using SKU, UPC, EAN and ISBN.

I would like to add a new feature to be able to search using other ID type (not just ASIN).

Reference:
http://docs.aws.amazon.com/AWSECommerceService/latest/DG/ItemLookup.html
http://docs.aws.amazon.com/AWSECommerceService/latest/DG/APPNDX_SearchIndexValues.html

All test passed.

Thank you.