feat: adds endpoints 'client contacts' and 'contacts' and integration tests for all existing endpoints.

src/ClientContacts/Models/GetClientContactsResponse.cs

@@ -0,0 +1,9 @@
+using System.Collections.Generic;
+
+namespace Novaloop.PaymoApi.ClientContacts.Models
+{
+    public class GetClientContactsResponse
+    {
+        public IEnumerable<PaymoClientContact> ClientContacts { get; set; }
+    }
+}