Correct shipping address set/get docs

The document comments actually power what classes are instantiated when parsing the API responses
Merge branch 'master' of github.com:miketramontano/rest-api-sdk-php into miketramontano-master

Update Address to ShippingAddress for PayerInfo
Change address to shipping address in tests
Merge branch 'miketramontano-master'

Merge in Shipping Address docs change