Raise an exception on connection creation if site is None.
Raise an exception on connection creation if site is None.

asiviero/shopify_python_api,gavinballard/shopify_python_api,Shopify/shopify_python_api,ifnull/shopify_python_api,varesa/shopify_python_api,SmileyJames/shopify_python_api,metric-collective/shopify_python_api