Compress HTML documentation into a zip file.

def zip_html(self):
        """
        Compress HTML documentation into a zip file.
        """
        zip_fname = os.path.join(BUILD_PATH, 'html', 'pandas.zip')
        if os.path.exists(zip_fname):
            os.remove(zip_fname)
        dirname = os.path.join(BUILD_PATH, 'html')
        fnames = os.listdir(dirname)
        os.chdir(dirname)
        self._run_os('zip',
                     zip_fname,
                     '-r',
                     '-q',
                     *fnames)