Add option to generate //$NON-NLS-1$

[foal]

Generate //$NON-NLS-1$ for toString method, e.g.

    public String toString() {
        return MoreObjects.toStringHelper(this)
                .add("super", super.toString()) //$NON-NLS-1$
                .add("offset", offset) //$NON-NLS-1$
                .toString();
    }

[foal]

Or simple add @SuppressWarnings("nls") before method