Added support for window targeting (example: '_blank')

#### Window targets ####
Now redirect can target windows
```
$.redirect('create-knowledge-asset.php', data, 'POST', '_blank');
````
This will open a new window and post data to it. 

##### Backwards compatible #####
If the last argument is left out, it becomes empty string, which is default behavior (redirect in same window).
```
$.redirect('create-knowledge-asset.php', data, 'POST');
````

##### target #####
The previously-named variable *target* was renamed *url* to avoid confusion, because in &lt;form&gt; the *target* attribute refers to a window.
```
<form ... target="_blank">
```