Each webrunner provides a public directory which is useful to develop and deploy your HTML5 applications (read more about this public directory here).
This directory is served by an apache2 web server. The default configuration allows you to extend it with your own rules. To do so, please create a .htaccess file at the root of the public directory.
You can read more about the configuration of an apache2 webserver there : http://httpd.apache.org/docs/current/en/howto/htaccess.html
Here is an example of a .htaccess file that you can use in your own webrunner :