Avoid assigning when we don't need to

Signed-off-by: Tim Smith <tsmith@chef.io>

Signed-off-by: Pete Higgins <pete@peterhiggins.org>

Legally incredibly dubious, particularly since we don't follow it
strictly as policy, and we have git history instead, which does it right.
This is just a waste of time and a cargo cult.

Signed-off-by: Lamont Granquist <lamont@scriptkiddie.org>

Signed-off-by: Lamont Granquist <lamont@scriptkiddie.org>

This update found a few things that should have been triggering before.

Signed-off-by: Tim Smith <tsmith@chef.io>

 - Fix to_json Wrong number of argument while calling on object of Node::Attribute.
 - Allowed to_yaml method in Node::Attribute.

Signed-off-by: Vivek Singh <vivek.singh@msystechnologies.com>

We have four different versions of this now, and this converts to
just using the one convention in `lib/chef/constants.rb`

Interestingly `Chef::NIL_ARGUMENT` is used nowhere in the codebase, that
probably got refactored out in 12.5.1.

Node objects still use `NIL` but that is a different kind of `Object.new`
which really is semantically private to the implementation of
attributes.

Signed-off-by: Lamont Granquist <lamont@scriptkiddie.org>

convert kind_of? to is_a?

Signed-off-by: Lamont Granquist <lamont@scriptkiddie.org>

start enforcing using %i{} instead of arrays of symbols

Signed-off-by: Lamont Granquist <lamont@scriptkiddie.org>

i like this one, gives visual priority to returns or raises that are
buried in the middle of things.

Signed-off-by: Lamont Granquist <lamont@scriptkiddie.org>