join `path` and `saltenv` into a 'salt://' URL.

def create(path, saltenv=None):
    '''
    join `path` and `saltenv` into a 'salt://' URL.
    '''
    if salt.utils.platform.is_windows():
        path = salt.utils.path.sanitize_win_path(path)
    path = salt.utils.data.decode(path)

    query = 'saltenv={0}'.format(saltenv) if saltenv else ''
    url = salt.utils.data.decode(urlunparse(('file', '', path, '', query, '')))
    return 'salt://{0}'.format(url[len('file:///'):])