Facter task assumes facter is on path

The facter task runs in the Puppet ruby but shells out to the facter binary.

https://github.com/puppetlabs/puppetlabs-facter_task/blob/master/tasks/init.rb#L8

This means if facter isn't on the path then it won't run successfully, eg. resulting in a stack trace on bolt like:

/opt/puppetlabs/puppet/lib/ruby/2.4.0/open3.rb:199:in `spawn': No such file or directory - facter (Errno::ENOENT)

        from /opt/puppetlabs/puppet/lib/ruby/2.4.0/open3.rb:199:in `popen_run'

        from /opt/puppetlabs/puppet/lib/ruby/2.4.0/open3.rb:95:in `popen3'

        from /opt/puppetlabs/puppet/lib/ruby/2.4.0/open3.rb:258:in `capture3'

        from /tmp/tmp.a9S6TsO28X/init.rb:9:in `get'

        from /tmp/tmp.a9S6TsO28X/init.rb:18:in `<main>'

Note that given the Puppet dependency, Facter has a Ruby interface which could be used rather than shelling out. Alternatively the documentation could make it clear facter needs to be on the path and the module could provide a more user friendly error to make the route cause clear.