[COOK-3398] Directly access node attributes in templates

Foodcritic rule FC034 advocates the removal of unused template variables. In multiple situations, we have removed template variables that were actually used by a sub-sub template or a different platform. To minimize this (and to reduce code duplication), directly access unmodified node attributes in the templates themselves.
Add Test Kitchen, ChefSpec, RuboCop, and Foodcritic on Travis CI

Signed-off-by: Seth Vargo <sethvargo@gmail.com>