Fix EZP-20862: YUI3 JS/CSS files fail to load in non vhost setup

JIRA issue: https://jira.ez.no/browse/EZP-20862

# Description

In non virtual host setup, the path of the JS/CSS files build by the YUI3 loader are wrong because of a hardcoded path in ezyuiconfig.js. This patch changes the configuration to be dynamic so that this path is correct in different setups.

# Tests

manual tests