Add chmod in sftp feature

src/Ssh/Sftp.php

@@ -238,6 +238,21 @@ public function listDirectory($directory, $recursive = false)
         );
     }
 
+    /**
+     * Creates a directory
+     *
+     * @see http://php.net/manual/en/function.ssh2-sftp-chmod.php
+     *
+     * @param  string $filename The filename to resolve
+     * @param  int    $mod      The permissions on the new filename
+     *
+     * @return Boolean
+     */
+    public function chmod($filename, $mod = 0600)
+    {
+        return ssh2_sftp_chmod($this->getResource(), $filename, $mod);
+    }
+
     /**
      * {@inheritDoc}
      */