Properly install commands.cfg too
icinga-phpapi package is gone now
Ensure that /etc/icinga/stylesheets is not purged

On Debian/Ubuntu CSS files are installed under /etc for easy
customisation
Also distribute resource.cfg file
Take care of /etc/icinga/modules directory too
Allow to customize process_performance_data

Beaware that the default is now 0
Add a parameter for host_perfdata_file and service_perfdata_file

Set that parameter to undef so performance data are not written to disk
by default
Add parameter for host_perfdata_file_processing_command and service_perfdata_file_processing_command