Implement observable oauth client

Rx will never die

Octokit.Reactive/Clients/IObservableOauthClient.cs

@@ -0,0 +1,28 @@
+using System;
+
+namespace Octokit.Reactive
+{
+    public interface IObservableOauthClient
+    {
+        /// <summary>
+        /// Gets the URL used in the first step of the web flow. The Web application should redirect to this URL.
+        /// </summary>
+        /// <param name="request">Parameters to the Oauth web flow login url</param>
+        /// <returns></returns>
+        IObservable<Uri> GetGitHubLoginUrl(OauthLoginRequest request);
+
+        /// <summary>
+        /// Makes a request to get an access token using the code returned when GitHub.com redirects back from the URL
+        /// <see cref="GetGitHubLoginUrl">GitHub login url</see> to the application.
+        /// </summary>
+        /// <remarks>
+        /// If the user accepts your request, GitHub redirects back to your site with a temporary code in a code
+        /// parameter as well as the state you provided in the previous step in a state parameter. If the states don’t
+        /// match, the request has been created by a third party and the process should be aborted. Exchange this for
+        /// an access token using this method.
+        /// </remarks>
+        /// <param name="request"></param>
+        /// <returns></returns>
+        IObservable<OauthToken> CreateAccessToken(OauthTokenRequest request);
+    }
+}