Ask user which noble to choose if multiple are earned.

#### Test plan
Buy a bunch of cards until multiple nobles can be selected.

To make this easier:
```
// GameData.js
var nobles = [
  {cost: {black: 1, white: 1}, points: 3},
  {cost: {black: 1, red: 1}, points: 3},
};
```
Buy a red, a white, then a black card. Choose your noble. You should only get one.

Why did you remove this?  What if it is undefined?  Are you sure the if below will throw an error?  Maybe this isn't the best way to accomplish this but you can't lose functionality.