Rename variable quantityPickerIndexPath -> pickerIndexPath
Add display order to maltAddition CoreData object

This conflates UI with the model a little bit, but it would be
too much work to build some separate UI sorting component.
This will eventually be used to persist the ordering of malts
across sessions. It also might simplify some of the table view
code a bit (not having to separate malt lists).
Malts are now sorted in a user-defined order

No longer sorting by malt addition weight and name.
TBD: allow the user to reorder the additions.

I think having a user defined order is the way to go.
It will fit the user's mental model the best, and they won't
be surprised by an automatic sorting.
Fixed minor compiler warning
Simplify OBIngredientDashboardController

This controller previously tried to allow itself to be reused
for both displaying a table of hops and a table of malts.
These two ingredient types are two different to lend themselves
to be reused. This complicated the code more than it helped.

The next commit will rename the view controller to make it clear
that it supports displaying malts rather than general ingredients.
Rename OBIngredientDashboardController -> OBMaltAdditionViewController
Remove unused OBMaltAttributeSelector .h, .m, and .xib