[Chapter 15] Bug - BST remove method isn't performing correctly in removing nodes.  

BinarySearchTree.prototype.remove fails to remove parent node in the following example.

example
```js
var bst1 = new BinarySearchTree();
bst1.insert(1);
bst1.insert(3);
bst1.insert(2);
console.log(bst1.findNode(3)); // true
console.log(bst1.findNode(5)); // false

bst1.remove(1);
bst1.remove(3);
bst1.remove(2);
console.log(bst1.findNode(1));  // true <-- should be false
```