Iptables is blocking forwaded ports

When setting forwarded ports on a RHEL/CentOS VM, Iptables is blocking any ports other than 80, 443 & 22. This will add ALLOW rules to Iptables to allow any forwarded ports to be accessible.
Adding if-block around iptables_port call

Adding an if-block to ensure that the ```$vm_values['vm']['network']['forwarded_port']``` configuration option has been set.
Merge branch 'patch-2' of https://github.com/trickeyone/puphpet into trickeyone-patch-2
Passes VM target type as a facter