[ic] add fixed weight onto shipping weight total

[interchange-users@icdevgroup.org (Jeff Dafoe)]

> I don't think that you can be 'ultra-accurate' on shipping costs. Or, need
> to be.

    I don't see any reason that it wouldn't be possible to charge at the
actual rate.  The only deviances I am having between IC-calculated cost and
actual cost are due to packaging weight.
    As for the need, that's a business decision.  The software operates
around the business requirements, not vice-versa.

Thanks,
Jeff