Write acceptance tests for task board

# Problem

We need to write some acceptance tests for the task board, at least ensuring that:

- the data renders correctly for boards and cards
- ordering of lists works correctly
- you can click on a task to go to the task page

What would be nice, although it is hard:

- test that updating the data from the server updates the UI, even if tasks are repositioned
- test dragging the cards (not sure of how to drive the drag events)