Default recipe for attribute-driven configuration

[bodgix]

This commit adds the default recipe which creates
hosts file entries based on a node attribute.

This new functionality can simplify the use of
the hosts file cookbook in some cases because
it makes managing the hosts file possible with
just data.

Issue: #85

[tas50]

This seems like a real anti-pattern since this cookbook provides a resource and should be used as a library cookbook.

[bodgix]

In my company, we don't have applications that need to manage /etc/hosts. We just need to manage it for a host.

If configuring /etc/hosts was a part of some bigger thing, like for example, cookbook_my_wordpress_blog needed to manage /etc/hosts for the wordpress app, we would call resources provided by hostsfile from there.

But since it's not the case, and in our case there isn't any reasonable place we could call the resources from we decided it made more sense to add a default recipe instead of creating a cookbook for example mycompany_hostsfile whose only purpose would be to define one resource.

[bodgix]

@bby-bishopclark I gave it another go and fixed the CI warning which I knew how.

This CI error:

libraries/entry.rb:129:5: W: Lint/DuplicateMethods: Method HostsFile::Entry#priority= is defined at both libraries/entry.rb:94 and libraries/entry.rb:129.
    def priority=(new_priority)
    ^^^

Is not related to my change. Must have been there before.

Not sure if this change gets merged anyway. We've been using this version at my company but we do not require it is merged into upstream because we don't depend on the supermarket so we're happy with continuing to use a fork.