Add section describing OCFL Object ZIP

[zimeon]

We currently talk about a zipped object only in the definition of OCFL Object Root. I think we need a new 3.x section on this (maybe 3.9)

[awoods]

I could see this new section being either 3.9 or 3.1.1.

[zimeon]

Yes, maybe 3.1.1 would be better. Message of that numbering is that the object structure is the same, expanded or zipped, but this is a packaging option

[ahankinson]

Editors Call Oct. 3 2018: Decision was to defer all reference to zipping in OCFL