Add initial resources.md for discussion

The first draft of a Kubernetes resource model.
Thanks, Tim.

Changes made, and new version pushed to my repository.
Daniel: please can you do the merge?  I got a verbal LGTM from Tim, but he
was in the car on the way to somewhere out of cellphone range :-).

Issues addressed in this revision:

   - millicores vs cores? Done: pros and cons described
   - What happens if size of pod != size of containers? Done.  (It's now a
   bug, but can be relaxed later.)
   - Change resource typename default "namespace" to be
   kubernetes.io/resources to allow greater future flexibility, and changed
   format to use RFC 3986 (URI) spec.
   - Clearer distinction between "external" and "internal" uses of
   fixed-point values, and when floating point is OK.
   - Removed exponent notation (5.6e4) - we can always add it back.
   - Removed u (micro) suffix.
   - Clarified that unbounded may mean somewhat undefined.
   - Added exponent-scaling notation for things like milli-units
   - Added a note about disquiet with disk naming to provoke discussion
   (it's in the "futures" section).

outstanding stuff:

   - ensuring that the examples are strictly correct YAML (or JSON)
   - fixing any new typos I introduced.

Let's get this out there for wider discussion/feedback.
Thanks,
  john