To make sure that it will work on Windows I think it has to be included in the `"` and also since there is a symlink inside the `node_modules/.bin` folder just do that:

    os.system('"%s" bower' % file_grunt)

where `file_grunt` is

   file_grunt = os.path.join(dir_bin, FILE_GRUNT)

Like the rest of them and at one point I might simplify that.. but for now just to be consistent do that if you don't mind..