Refactored FoA and FedEx to use correct settings. Refactored constants in Fedex. Created and got usps working
Merge pull request #710 from koswesley/USPS-1.3.0

Refactored FoA and FedEx to use correct settings. Refactored constants i...
Finishes CustomerService and adds a few extension methods to ICustomer
Integration tests for CustomerService and CustomerAddressService via new extension methods.
Merge remote-tracking branch 'merchello/1.3.0' into 1.3.0
Patches unit tests when run for the entire solution