Load needed product attributes and similar products from Amazon API

* Add get_attribute_hash method in ProductLookup module, which returns relevant attributes from Amazon API query
* Add get_similar_products method in ProductLookup module, which returns array of similar product ASINs given by Amazon API
*load_from_asin method now returns a hash, consisting of a products_attributes hash, and the similar products ASIN array
Merge branch 'product_lookup' of https://github.com/ShopIt2Me/sitm into product_lookup
Add query for medium and small image sizes
Add get_ten_asins method in ProductLookup module. Returns randomly generated array of ten ASINs.