Add client for organization outside collaborators (#1639)

* Add client for organization outside collaborators

* Add unit/integration tests

* Add methods for removing an outside collaborator

* Add unit/integration tests

* Add new Put method to Connection which accepts a preview header

* Add methods for converting an org member to an outside collaborator

* Fix copy paste errors in new exceptions

* According to API docs, a 403 should be returned if the member is not a member of the org, but a 404 is actually returned

* Add unit/integration tests

* Remove unused using directives

* Got a bit overzealous with my removal of using directives

* Fix integration tests by using the configured Organization and test username rather than henrik's :)

* Remove ApiOptions overloads as it isn't currently supported

* Fix XML doc grammar

* Fix failing unit tests

* Missed a couple of nameof replacements

Octokit/Http/Connection.cs

@@ -430,6 +430,21 @@ namespace Octokit
             return response.HttpResponse.StatusCode;
         }
 
+        /// <summary>
+        /// Performs an asynchronous HTTP PUT request that expects an empty response.
+        /// </summary>
+        /// <param name="uri">URI endpoint to send request to</param>
+        /// <param name="accepts">Specifies accepted response media types.</param>
+        /// <returns>The returned <seealso cref="HttpStatusCode"/></returns>
+        public async Task<HttpStatusCode> Put(Uri uri, string accepts)
+        {
+            Ensure.ArgumentNotNull(uri, nameof(uri));
+            Ensure.ArgumentNotNull(accepts, nameof(accepts));
+
+            var response = await SendData<object>(uri, HttpMethod.Put, null, accepts, null, CancellationToken.None).ConfigureAwait(false);
+            return response.HttpResponse.StatusCode;
+        }
+
         /// <summary>
         /// Performs an asynchronous HTTP DELETE request that expects an empty response.
         /// </summary>

Octokit/Http/IConnection.cs

@@ -214,6 +214,14 @@ namespace Octokit
         /// <returns>The returned <seealso cref="HttpStatusCode"/></returns>
         Task<HttpStatusCode> Put(Uri uri);
 
+        /// <summary>
+        /// Performs an asynchronous HTTP PUT request that expects an empty response.
+        /// </summary>
+        /// <param name="uri">URI endpoint to send request to</param>
+        /// <param name="accepts">Specifies accepted response media types.</param>
+        /// <returns>The returned <seealso cref="HttpStatusCode"/></returns>
+        Task<HttpStatusCode> Put(Uri uri, string accepts);
+
         /// <summary>
         /// Performs an asynchronous HTTP DELETE request that expects an empty response.
         /// </summary>