Add support for updateAccountType

Our account representative let us know that sometimes an account can fall into an 'OTHER' category. In this case they will not be able to get transactional data for the account, but all aggregation dates and codes look to be valid. 

This PR adds support for the updateAccountType call in order to categorize the 'other' accounts. Intuit's documentation on the call can be found here:

https://developer.intuit.com/docs/0020_customeraccountdata/customer_account_data_api/0020_api_documentation/0070_updateaccounttype

Please let me know if you have any questions.