fix creating sub-folders in plugins

plugin_installer/manifest.ini

 [info]
 name: Plugin Installer
 short_name: plugin_installer
-version: 0.11.9
+version: 0.11.10
 description: Install and upgrade plugins from ftp
 authors: Denis Fomin <fominde@gmail.com>
  Yann Leboulanger <asterix@lagaule.org>

plugin_installer/plugin_installer.py

@@ -616,6 +616,7 @@ class Ftp(threading.Thread):
 
             # creating dirs
             for dir_ in dirs:
+                dir_ = dir_.replace(self.plugin.server_folder, 'plugins')
                 if os.path.exists(os.path.join(local_dir, dir_)):
                     continue
                 os.mkdir(os.path.join(local_dir, dir_))