Remove $dhcp_reverse
Improved header in settings.yml template
Improved header in settings.yml template
Use parametrized style of the dns class

Also expose the dns_forwarders parameter with it
Move tftp files out of case statement since they are the same on both platform
Parametrize the foreman-proxy port
Prefix all tftp params with tftp_
Prefix all dhcp parameters with dhcp_
Allow use of sudoers.d
Disable sudoers.d for EL5, doesn't exist by default