Suffix for more friendly url

Hi, this is not an issue, rather it is a pull request, but did not know how to add it. I apologize.

I love this framework because it is a basis for any project and is very light.

It would be great to add a suffix to the friendly url.

For example:
http://mysite.com/about/index.php
http://mysite.com/about/company.php
or
http://mysite.com/about/index.html
http://mysite.com/about/company.html
