Fix reference to non-existent group-raven file in nagios config

Also whitespace errors.
Fix variables in nagios to use @
Update apache module to fix @ variables
Update munin templates to use @ variables
Fix unattended-upgrades to use @ variables
Add missing @s to variables in nagios templates
Add missing newlines to server.cfg.erb in nagios
Add missing @ to nagios server.cfg.erb
Update sudoers submodule to fix for @ variables