Allow the import of purchase order lines without specifying price

Hi,

at the moment when importing a csv into a purchase order you have to specify SKU, Quantity and Price. You get an error if you try to import the file with a blank price, which is an issue for us as we would like to import the csv from our order forecasting, which does not have supplier pricing info.

The price isn't required as Dear could enter the price automatically, the same as it does when manually entering products line by line.

In the sales module it is possible to get around this by importing the file with a dummy price and then pressing apply discounts, however the same workaround isnt't available for puchases.

Thanks