Fix EZP-22592: Setup wizard should check for php-xsl and php-intl

> [EZP-22592](http://jira.ez.no/browse/EZP-22592)

Adds checks for ext-intl and ext-xsl to the setup wizard.

![setup_wizard_extensions_checks](https://cloud.githubusercontent.com/assets/235928/2658317/d696f9ba-c006-11e3-9b77-590532706b03.png)