added User::organizations, to be able fetch user's organizations

Author: cystbear

lib/Github/Api/User.php

@@ -51,6 +51,18 @@ public function show($username)
         return $this->get('users/'.rawurlencode($username));
     }
 
+    /**
+     * Get extended information about a user by its username
+     * @link https://developer.github.com/v3/orgs/
+     *
+     * @param  string $username the username to show
+     * @return array  information about organizations that user belongs to
+     */
+    public function organizations($username)
+    {
+        return $this->get('users/'.rawurlencode($username).'/orgs');
+    }
+
     /**
      * Request the users that a specific user is following
      * @link http://developer.github.com/v3/users/followers/