Added KnockoutObservableArray.Push([]) support in addition to open-ended function arguments

You can now pass in a plain array in to KnockoutObservableArray.push. The existing type definition only supported open-ended function arguements like this:
```myObservableArray('foo', 'bar')```
This change allow you to pass in an array like this:
```myObservableArray.push(['foo', 'bar'])```