Move to rundeck_version as a fact

[jyaworski]

Tagging @liamjbennett and @igalic.

I don't think that the fact existing on the systems is bad; I took this code almost directly from https://github.com/voxpupuli/puppet-collectd/blob/master/lib/facter/collectd_version.rb and it works fine. I actually ran into some errors because of the !defined in the facts class here.

[bastelfreak]

Thanks for the contribution.

things that came up my mind:

• rd-acl is available but not in $PATH
• fact pollutes other nodes

first thing is prevented, @jyaworski told me that the binary is always placed in /usr/bin which is guaranteed by the deps/rpms. second thing is not an actual thing because the fact is nonexistend if the binary isn't found

[jyaworski]

As a general note, I'm aware of fact pollution. There's really no good solution until environment isolation happens. This fact isn't heavy at all; if it were network or something, I'd consider it more heavily.

[bastelfreak]

I'm fine with the fact. it gets execuded on all nodes but not created. 👍 from my side