If merge is happening across the precedence levels (i.e. default, override, etc...)
     Pick the array from the higher precedence level
  If merge is happening at the same precendence level (i.e. when we are merging role default attribute with node default attributes)
     Concatanate the arrays.

- this is compatible with gem versions from 10.28.0 with minimal
  changes.
- mixlib-shellout differs in windows-versus-unix due to version pinning
  in windows-pr picking up old mixlib-shellout on windows, this is
  not fix, and left similar to 10.28.0
- gem versions should be levelled up for 10.30.x and beyond
- newly built 10.28.0 will pick up new mixlib-config 2.0 which is
  a delta from the downloadable omnibus builds, 10.28.2 will not
  pick up mixlib-config 2.0

This reverts commit 2a4ae8fe7c4b406a30f2c9e8257a20504dba9236.

- allows us to explicitly version pin in the gemspec on gem installs
  rather than getting different behavior from 'gem install' and
  'bundle install' (gemspec vs. Gemfile).
- the mingw deps had been in the Gemfile because it needed to be a
  group since gemspecs do not have groups.  this builds two different
  gems for publication to rubygems instead.
- see mixlib-shellout for the prototype of where this has been done
  (successfully).