configurable $config_director_dirs with purge option

[benibr]

I currently have a setup where a lot of client/job configs are submitted by external tools via Bareos configure command.
Sadly the next Puppetrun purges them all as the whole directory tree is managed by config_director_dirs [1]
I'd like to either configure config_director_dirs via a class parameter or disable the purge option or both.

I can submit a patch next week which makes the config_director_dirs variable configurable.
I'm not sure if the purge option is really nessesary.

[1] https://github.com/voxpupuli/puppet-bareos/blob/master/manifests/director.pp#L35