Install the xsltproc package, remove the deprecated 'sudo' keyword and
specify the Linux distribution explicitly.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
This change makes it possible to tell Travis CI to trigger a build after
every push and every time a new merge request is submitted.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>