mixlib-shellout update to 1.6.1

* Update lockfile for repo to pin 1.6.1
* pull in 1.0.68 of oc-chef-pedant which contains the same change

update oc-chef-pedant to version w/ correct mixlib
Merge pull request #628 from opscode/mixlib-shellout-1.6.1-12.0

mixlib-shellout update to 1.6.1