Add exception handling for non-OK status codes

Octokit/Exceptions/AuthorizationException.cs

@@ -0,0 +1,36 @@
+using System;
+using System.Net;
+using System.Runtime.Serialization;
+
+namespace Octokit
+{
+    /// <summary>
+    /// Exception thrown when we receive an HttpStatusCode.Unauthorized (HTTP 401) response.
+    /// </summary>
+#if !NETFX_CORE
+    [Serializable]
+#endif
+    public class AuthorizationException : ApiException
+    {
+        public AuthorizationException()
+        {
+        }
+
+        public AuthorizationException(string message)
+            : base(message, null, HttpStatusCode.Unauthorized)
+        {
+        }
+
+        public AuthorizationException(string message, Exception innerException)
+            : base(message, innerException, HttpStatusCode.Unauthorized)
+        {
+        }
+
+#if !NETFX_CORE
+        protected AuthorizationException(SerializationInfo info, StreamingContext context)
+            : base(info, context)
+        {
+        }
+#endif
+    }
+}