Add a way for donors to select quantity to donate (if donating to an organization)

[calexity]

As a donor
When I'm looking at donation needs
And I'm looking at a group of items an organization asked for
I want to be able to say I'm donating more than one but maybe not all of the items.

Notes
Donors should have more flexibility when donating to one organization - maybe they want to donate more than one thing but not donate all the things needed