Implement GetOrCreateApplicationAuthentication

Implements the endpoint for creating an application authorization token.

Octokit/Helpers/TwoFactorChallengeResult.cs

@@ -0,0 +1,27 @@
+using System.Diagnostics.CodeAnalysis;
+
+namespace Octokit
+{
+    public class TwoFactorChallengeResult
+    {
+        [SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes",
+            Justification = "It really is immutable yo!")]
+        public static readonly TwoFactorChallengeResult RequestResendCode = new TwoFactorChallengeResult(null, true);
+
+        public TwoFactorChallengeResult(string authenticationCode)
+            : this(authenticationCode, false)
+        {
+            Ensure.ArgumentNotNull(authenticationCode, "authenticationCode");
+        }
+
+        TwoFactorChallengeResult(string authenticationCode, bool resendCodeRequested)
+        {
+            AuthenticationCode = authenticationCode;
+            ResendCodeRequested = resendCodeRequested;
+        }
+
+        public bool ResendCodeRequested { get; private set; }
+
+        public string AuthenticationCode { get; private set; }
+    }
+}