Add imgur authentication options

Owin.Security.Providers/Imgur/ImgurAuthenticationDefaults.cs

@@ -1,6 +1,6 @@
 namespace Owin.Security.Providers.Imgur
 {
-    public class ImgurAuthenticationDefaults
+    internal static class ImgurAuthenticationDefaults
     {
         public const string AuthenticationType = "Imgur";
     }

Owin.Security.Providers/Imgur/ImgurAuthenticationOptions.cs

@@ -1,11 +1,41 @@
 namespace Owin.Security.Providers.Imgur
 {
+    using System;
+    using System.Net.Http;
+
+    using Microsoft.Owin;
     using Microsoft.Owin.Security;
 
+    using Owin.Security.Providers.Imgur.Provider;
+
     public class ImgurAuthenticationOptions : AuthenticationOptions
     {
         public ImgurAuthenticationOptions() : base(ImgurAuthenticationDefaults.AuthenticationType)
         {
+            this.AuthenticationMode = AuthenticationMode.Passive;
+            this.BackchannelTimeout = TimeSpan.FromSeconds(60);
+            this.CallbackPath = new PathString("/signin-imgur");
+            this.Caption = ImgurAuthenticationDefaults.AuthenticationType;
         }
+
+        public ICertificateValidator BackchannelCertificateValidator { get; set; }
+
+        public HttpMessageHandler BackchannelHttpHandler { get; set; }
+
+        public TimeSpan BackchannelTimeout { get; set; }
+
+        public PathString CallbackPath { get; set; }
+
+        public string Caption { get; set; }
+
+        public string ClientId { get; set; }
+
+        public string ClientSecret { get; set; }
+
+        public IImgurAuthenticationProvider Provider { get; set; }
+
+        public string SignInAsAuthenticationType { get; set; }
+
+        public ISecureDataFormat<AuthenticationProperties> StateDataFormat { get; set; }
     }
 }