Add extra setting for forward headers

[Ultimation]

Rundeck bug: https://github.com/rundeck/rundeck/issues/3840

Add server.useForwardHeaders=true as a possibility into the puppet module to work around this rundeck bug.

Depending on the rundeck version installed, the java flag may be required

[sgohl]

is this still in progress?

Using Docker, this is a requirement, since there is no way of modifying the rundeck-config.properties directly.