Implement Create commit method

Octokit.Reactive/Clients/IObservableCommitsClient.cs

@@ -17,6 +17,19 @@ namespace Octokit.Reactive
         /// <returns></returns>
         [SuppressMessage("Microsoft.Naming", "CA1716:IdentifiersShouldNotMatchKeywords", MessageId = "Get",
             Justification = "Method makes a network request")]
-        IObservable<Commit> Get(string owner, string name, string reference);        
+        IObservable<Commit> Get(string owner, string name, string reference);
+
+        /// <summary>
+        /// Create a commit for a given repository
+        /// </summary>
+        /// <remarks>
+        /// http://developer.github.com/v3/git/commits/#create-a-commit
+        /// </remarks>
+        /// <param name="owner">The owner of the repository</param>
+        /// <param name="name">The name of the repository</param>
+        /// <param name="commit">The commit to create</param>
+        /// <returns></returns>
+        IObservable<Commit> Create(string owner, string name, NewCommit commit);        
+    
     }
 }