Implement get products (aliexpress.affiliate.product.query)

[sima96]

The function get products is not implemented.

The structure of query is writed but in the api.py there isn't the function for use it.

I add in api.py the function get_products that invoke the AliexpressAffiliateProductQueryRequest.

Can i commit it for new version of library?

[sergioteula]

Yes sure, you can always pull request and help working on this repo.

[BackrndSource]

Done in PR #30