these code are ugly and mostly duplicated.
```
if compressor == 'all' or options.compressor == 'js':
  js_list = GetFileList(app_root, js_ext)
  js_bk_list = BackupFile(app_root, backup_dir, js_list)
  compress_js_and_css.CompressJavaScript(js_list)

if compressor == 'all' or options.compressor == 'css':
  css_list = GetFileList(app_root, css_ext)
  css_bk_list = BackupFile(app_root, backup_dir, css_list)
  compress_js_and_css.CompressCss(css_list)
```
wouldn't it be clearer?