Draggable Ranked Ballots

[fsargent]

Add draggable ballot election setting

• for now we'll keep the grid as a default, but dragging is a better interface so I bet we'll update the default later, (especially for ranked ballots)
• Here's a recent feature that included adding an election setting: aa8c901

Implement draggable ballots for RCV elections
Samuel did something similar for reordering candidates in the race creation flow, so you can use a different approach)

Draggable ballots with equal rankings
This will be similar to the interface on https://tiermaker.com/ , and would be a better for STAR or Approval races
The first iteration doesn't need to support this, but keep in mind that it could be extended to this later

Pictures
We don't have candidate photos working yet, but in the future this could be extended to having draggable items with only the pictures