format date with local support
    ``d``: datetime to format
    ``fmt``: format, default is '%Y-%m-%d %H-%M'
    ``local``: format as local time

def fmt_datetime(d, fmt='', local=True):
    """
    format date with local support
    ``d``: datetime to format
    ``fmt``: format, default is '%Y-%m-%d %H-%M'
    ``local``: format as local time
    """
    if not d:
        return ''
    if local:
        from django.templatetags.tz import localtime
        d = localtime(d)
    if not fmt:
        fmt = '%Y-%m-%d %H-%M'
    return d.strftime(fmt)