Platform support policy proposal

There is a fair amount of confusion about the specific operating system platforms, platform versions, etc. that Chef Software, Inc. supports for its products. This RFC will clarify this by calling out the individual operating systems and their releases as explicitly supported or not.
I (and others besides @aglarond) would also love to see at least best-effort Tier 2 support for the SmartOS Illumos distro.  It's one of the few cloud-specific OSes in the open source world, and lots of SmartOS users (including the parent company, Joyent) also use Chef heavily.

I'd be more than happy to contribute some of my at-work time to getting this into Omnitruck for automatic knife bootstrapping, if someone from Chef can just point me in the right direction WRT contribution.  Omnibus/Omnitruck is a bit daunting for a newcomer.  CC/ @someara @sax as I've discussed this with both of them before more than once.

Also note that a lot of the code we'd need for this would likely be cross-platform across all Illumos distros (OmniOS, SmartOS, OpenIndiana), and we might even be able to re-use some of the Omnibus build code for Solaris.  So with the right guidance, we might be able to wrap this pretty quickly and get benefits across many platforms.

Lastly, note the work that's happening here: https://github.com/sax/vagrant-smartos-zones