COOK-1170 - Fixes in response to GH line comments.

Responded to comments in pull request:
- Updated .kitchen.yml
- Updated Berksfile with pessimistic locks for all bundled cookbooks.
- Updated Gemfile with pessimistic locks for all bundled gems.
- Updated minitest files, removed unnecessary boilerplate.
- recipes/ntpdate.rb reverted accidental double-comment
- Updated spec_helper.rb, simplified per comments.
- Updated spec test files per comments.
- Updated gitignore to ignore vendor/

In addition, fixed failing task in Rakefile