Installations: Add create access token endpoint

Author: naderman

lib/Github/Api/Installations.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace Github\Api;
+
+/**
+ * @link   https://developer.github.com/early-access/integrations/authentication/
+ * @author Nils Adermann <[email protected]>
+ */
+class Installations extends AbstractApi
+{
+    /**
+     * Create an access token for an installation
+     *
+     * @param int $installationId An integration installation id
+     * @param int $userId         An optional user id on behalf of whom the
+     *                            token will be requested
+     *
+     * @return array token and token metadata
+     */
+    public function createAccessToken($installationId, $userId = null)
+    {
+        $parameters = array();
+        if ($userId) {
+            $paramters['user_id'] = $userId;
+        }
+        return $this->post('/installations/'.rawurlencode($installationId).'/access_tokens', $parameters);
+    }
+}

lib/Github/Client.php

@@ -210,6 +210,11 @@ public function api($name)
                 $api = new Api\Gists($this);
                 break;
 
+            case 'installation':
+            case 'installations':
+                $api = new Api\Installations($this);
+                break;
+
             case 'issue':
             case 'issues':
                 $api = new Api\Issue($this);