Add Response Message to OpenTrackException

In order to add a customer to OpenTrack you must first search for it.  They provide an expiring token for you to use when calling the add customer method.  When you make a search that does not return results it gives an error response of CS02 "No customers matching search criteria.".  The OpenTrackApi object then throws an exception.  The data in the exception does not contain the "DataToken" element.

Since this "DataToken" concept might be unique to customers I did not want to add the specific property to the exception class.  Instead, I chose to include the full response so if there are other data elements in other error messages the client may need, they can query the response to find it.