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.
Agree @lamont-granquist but alternatively we will not know if we break something on OEL until someone hits our breakage. 

I'm :+1: for having a tester for every platform we claim Tier 1 support.