mailhost resource does not use ensure parameter, therefore cannot be made absent

[qs5779]

Affected Puppet, Ruby, OS and module versions/distributions

• Puppet: all
• Ruby: all
• Distribution: all
• Module version: i assume all, but only verified with latest/master

How to reproduce (e.g Puppet code you use)

define a mailhost resource using defaults, change ensure to absent

What are you seeing

The configuration file for the mailhost resource is not removed

What behaviour did you expect instead

I expected it to be removed

[alexjfisher]

Adding skip-changelog label so we don't get 2 almost identical entries appear. (one for the issue, one for the PR).