add sys_info resource to get information about the hostname

[chris-rock]

Adds the ability to requests the hostname of the current system:

describe sys_info do
  its('hostname') { should eq 'example.com' }
end

[chris-rock]

This is required for some Windows improvements for #990. We could also argue, this belongs into train

[chris-rock]

quickly discussed with @arlimus that this does not belong into train

[stevendanna]

You can elide the explicit return here if you want

[stevendanna]

👍 Left some minor, non-critical comments. It might be worth thinking about whether we want the same hostname, fqdn, and machinename split that ohai has. The pro of the split is that it makes the semantics of what gets returned a bit more consistent even when run on differently configured systems. The downside of the ohai method is that you need to understand the difference between those vaguely defined concepts since it doesn't map 1-to-1 with the command output.

Just food for thought.

[chris-rock]

@stevendanna lets add those features in another iteration. For now it simply returns what the system is telling us :-)