Add XSL extension

Summary:
D142 adds XSL extension to nasqueron/php-cli image.

As the XSL extension isn't CLI specific, we port the change to
nasqueron/nginx-php-fpm too, so we can get web and CLI coherent
environments.

Cf. T641.

Test Plan:
Build the image, run a container with php -i.

XSL should appear.

Reviewers: dereckson

Subscribers: Nasqueron Docker deployment squad

Projects: Docker images

Maniphest Tasks: T641

Differential Revision: http://devcentral.nasqueron.org/D143