Integrate Changes from Chef 10.18 into master (Chef 11)

Merged Chef 10.18 into this branch to generate a mergeable branch containing Chef 10.18's bug fixes and such.

There is a lot of churn in the manpages and such, but the changes to lib/ are all quite reasonable. This branch passes Ci for ruby 1.8/1.9 and windows+ruby 1.9.