Implement GetOrCreateApplicationAuthentication

Implements the endpoint for creating an application authorization token.

Octokit/Exceptions/AuthorizationException.cs

@@ -34,3 +34,42 @@ namespace Octokit
 #endif
     }
 }
+
+
+/*
+            [Fact]
+            public void CreatesGitHubErrorFromJsonResponse()
+            {
+                var exception = new ApiUnauthorizedWebException("{\"message\":\"Bad credentials.\"}");
+
+                exception.ApiUnauthorizedError.Message.ShouldEqual("Bad credentials.");
+                exception.ApiUnauthorizedError.Errors.ShouldBeNull();
+            }
+
+            [Theory]
+            [InlineData("")]
+            [InlineData(null)]
+            [InlineData("{{{{{")]
+            public void CreatesGitHubErrorIfResponseMessageIsNotValidJson(string responseContent)
+            {
+                var exception = new ApiUnauthorizedWebException(responseContent);
+
+                exception.ApiUnauthorizedError.Message.ShouldEqual(responseContent);
+                Assert.False(exception.RequiresSecondFactor);
+            }
+
+            [Fact]
+            public void CanPopulateObjectFromSerializedData()
+            {
+                var exception = new ApiUnauthorizedWebException("{message:\"Bad credentials.\"}");
+                using (var stream = new MemoryStream())
+                {
+                    var formatter = new BinaryFormatter();
+                    formatter.Serialize(stream, exception);
+                    stream.Position = 0;
+                    var deserialized = (ApiUnauthorizedWebException)formatter.Deserialize(stream);
+                    deserialized.ApiUnauthorizedError.Message.ShouldEqual("Bad credentials.");
+                    exception.ApiUnauthorizedError.Errors.ShouldBeNull();
+                }
+            }
+*/