Rename Address -> Zipcode
Update Zipcode attributes
Update client spec with new Zipcode#get parameters
Refactor rest_request on Brapi::Client
Zipcode#city is a City
Refactor Client#zipcode for extracting City
Add change notes about Zipcode GET
Update README about Zipcode object
Merge pull request #9 from Helabs/new-zipcodes-get

New zipcodes get