Fix handleURLSlashes() so that it's pretty-URLs-aware

Fixes the **handleURLSlashes()** method of the **Application** class so that with pretty URLs enabled, going to...

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mydomain.com/about/

...will properly redirect to...

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mydomain.com/about

...instead of...

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mydomain.com/index.php/about

-Steve