Disable diffs during file functional tests

No functional tests actually use the diff behavior and this speeds them
up quite a bit.
avoid clobbering original diff disable state when nested
forcibly turn diffing back on after diff tests
Support Win8/2k12 versions
Spec test to validate version.rb
minor fix. Check host caption
Merge branch 'adamed-oc-6536-clogeny-merge' of github.com:opscode/chef into adamed-oc-6536-clogeny-merge