bindingHandler.value's valueHasChanged field is 'false' but maybe should be 'true'  

Today I encountered the following issue: http://jsfiddle.net/philipooo/2mSNt/
I entered +1 into an text input which is bound to an computed observable. Internally I parseInt the input to get a number, and write it back to the computed behaviour. But the value bindingHandler doesnt recognize the change because it does this...

```js
var valueHasChanged = (newValue != elementValue);
```

...and as you know 1 == "+1" is true.

The text bindingHandler of the span (see example link) updates the value as expected.

Because I needed to solve the problem I extended the code like you did
it with the 'JavaScripts 0 == "" behavious..'

```js
if(typeof newValue === 'number' && newValue.toString() !==
elementValue)
    valueHasChanged = true;
```

Greetings