Substituting any classes containing Sdk with Api
Adding DwollaSdk class to abstract away api endpoints
Adding retrieve method for Transaction
Adding all method for Transaction
Adding implicit mappings
Adding retrieve method for Balance
Changing method names and response types for transaction related api calls so they are consistent
Adding retrieve method for User
Adding full retrieve method for User
Adding nearby method for User
Defining type for each api response
Making names of formats in DwollaApiResponseJsonProtocol consistent with their associated types