trying out d3

`directives.test.js` should test that we *use* the `shapes` service's `circle` function properly. I think it would make sense to test that we draw a circle for each state in the scope given to the directive. This can probably be as simple as checking that we draw, for eg, 5 circles if we have 5 states.

We could also check that we use the state information properly when drawing the circles, like the state titles, but I think we'd end up overlapping with the `circle` tests there, so I think just checking the number of circles drawn would be fine.