Represent dtypes without byte order, as earlier Java tickstore code doesn't support explicit byte order.

def _str_dtype(dtype):
        """
        Represent dtypes without byte order, as earlier Java tickstore code doesn't support explicit byte order.
        """
        assert dtype.byteorder != '>'
        if dtype.kind == 'i':
            assert dtype.itemsize == 8
            return 'int64'
        elif dtype.kind == 'f':
            assert dtype.itemsize == 8
            return 'float64'
        elif dtype.kind == 'U':
            return 'U%d' % (dtype.itemsize / 4)
        else:
            raise UnhandledDtypeException("Bad dtype '%s'" % dtype)