Put placeholders into files to abstract information

[fracappa]

Hi folks.

This issue is to report that there are many files which should be modified since they contain values that depends on the machines configurations they are going to applied on.

One of the biggest example is network IPs in inventories and in var files, where the values of these pieces of information depends on the network configuration of the target machines.

My suggestion is to put placeholders like <target-machine-IP> rather than explicit information like 192.1.1.1.

Regards,
Francesco