Fix 0 condition_from_value

[PascalBrouwers]

Can't get shipping rate when condition_from_value = 0

[wsagen]

Thanks for your contribution. Unfortunately we can't accept your PR because changing the from value to be greater than and equal to will mean every MatrixRate customer will have to reformat their CSV files.
We are implementing a change in our next release that will allow you to match on 0 for the weight_from/price_from column. You should use an "*" in this column instead of 0.
Details here - http://docs.shipperhq.com/matrixrates-filtering-on-weightpricequantity/