Rename client.User.Keys to client.User.GitSshKey

Mark client.User.Keys as [Obsolete]

Octokit.Reactive/Clients/IObservableUsersClient.cs

@@ -50,8 +50,17 @@ namespace Octokit.Reactive
         /// <remarks>
         /// See the <a href="http://developer.github.com/v3/users/keys/">Keys API documentation</a> for more information.
         ///</remarks>
+        [Obsolete("Ssh key information is now available under the GitSshKey property. This will be removed in a future update.")]
         IObservableUserKeysClient Keys { get; }
 
+        /// <summary>
+        /// A client for GitHub's User Keys API
+        /// </summary>
+        /// <remarks>
+        /// See the <a href="http://developer.github.com/v3/users/keys/">Keys API documentation</a> for more information.
+        ///</remarks>
+        IObservableUserKeysClient GitSshKey { get; }
+
         /// <summary>
         /// A client for GitHub's UserUser GPG Keys API.
         /// </summary>