Catch array count solution using [].reduce with missing initialvalue

The test array used for the array count test does not catch an implementation solution that use Array.prototype.reduce() with missing initial value.

That is, this (wrong) solution pass the test:
```js
count : function(arr, item) {
  return arr.reduce(function(prev, curr) {
    return curr === item ? prev + 1 : prev;
  });
}
```
By updating the test array the above (correctly) fail the test. By adding 0 as the initial value it will pass with the updated test array. (No changes needed to the js-assessment-answers implementation.)