Allow to override any template or file from calling playbook

[jonhattan]

It would be great to have the ability to adjust any template or file to suit one needs. This open users the possibility to adjust anything and drastically reduce issues/PR, frustration and disaffection :)

For example, I want to enable archives in filebeat.yml. The role doesn't provide a variable for that, and it's not maintenable to change it directly in the server config.