Add a resolv_conf resource to core

[tas50]

Core Chef Resource Checklist

Before suggesting a resource for inclusion please make sure your suggestion meets these criteria for resources built into Chef:

• Automates an operating system component that ships by default on systems such as authentication, raid, disk partitions, firewalls, containers, or virtualization systems.
• Does not attempt automate 3rd party applications such as database, web, or application servers, which are best suited for cookbooks due to their fast moving nature.

Describe the resource:

A resource that manages the contents of resolv_conf

Why should this be included out of the box?:

It's a pretty important thing to manage on boxes

What operating systems would it run on?

Debian

Current cookbook implementation:

we have a cookbook, but it doesn't support the .d form fo things