Tested and updated CustomFileds API and creating address for a josn client API

Tested with Mambu 3.3. on staging
2. Corrected and tested getCustomFileds API. Removed TODOs.

3. Tested creating address with Json API.
3.1 The address is created successfully in Mambu
3.2 Issue: the address info is not returned with the create client API
Response.  Need to use getClientDetails() to get all created info
Updated with correct config file
Merge pull request #22 from mdanilkis/master

Updated and tested Get CustomFileds API, as well as Creating Address for a JSON Client API