Brick placement update when adding

When you add a brick from the tray, it places it after the currently selected brick (if there is a selected brick).

Closes #1907
Perhaps better to use this:
```
var selectedBrick = card.querySelector(".brick.selected");
var next = selectedBrick ? selectedBrick.nextSibling : false;
if (selectedBrick && next) {
  card.insertBefore(newElement,next);
} else {
  card.appendChild(newElement);
}
```