Add/edit recipe ingredient

[robertwitt]

Add a new view controller to edit a recipe ingredient.

Sub-tasks

• [x] Create IngredientViewController and hook into storyboard.
• [x] The table view (with static content) should hold cells for the food entity and the quantity (label and numeric text field).
• [x] Clicking the food cell should push the new FoodsViewController onto the navigation stack.
• [x] The table view should show all foods in the database and be searchable by food name.
• [x] Both view controllers should report data changes and selections back to their parents.