chore: refactoring some code to introduce a common base class for all api classes

src/Clients/Models/ClientsResponse.cs

@@ -0,0 +1,11 @@
+using System.Collections.Generic;
+using Newtonsoft.Json;
+
+namespace Novaloop.PaymoApi.Clients.Models
+{
+    public class ClientsResponse
+    {
+        [JsonProperty("clients")]
+        public IEnumerable<Client> Clients { get; set; }
+    }
+}