Upgrade ohai to 7.0.0.rc.0
Fix chef spec infra to use OHAI correctly.
Fix the Ohai resource for Ohai 7.

Conflicts:
	spec/unit/provider/ohai_spec.rb
Remove the unneeded running of "os" plugin.
Merge pull request #1294 from opscode/master-ohai-7

Upgrade ohai to 7.0.0.rc.0.