Better Exception handling and display of error messages
Added API Exceptions to all calls (previously only GET calls) and if we receive a BadResponseException (4xx 5xx errors) we now correctly add the error from Exact to the message in the ApiException, so ApiException->getMessage() call will correctly display the error.
Ability to insert middlewares to the Guzzle Client
Allow insertion of middlewares for the Guzzle Client.
After creating the Connection object, use the insertMiddleWare method to add a middleware to the stack.