Fix omnibus build after new JUnit formatter

The new JUnit formatter requires nokogiri, so we need
to build nokogiri via omnibus to ensure liblzma, etc.
is built as part of the omnibus package instead of
`gem` picking up a system liblzma, such as on Mac OS X.

Also bumping ruby to 2.3.1 to match ChefDK.

Signed-off-by: Adam Leff <adam@leff.co>

omnibus/Gemfile

@@ -12,7 +12,7 @@ source 'https://rubygems.org'
 
 # Use entries from chef's Gemfile
 gem 'omnibus', github: 'chef/omnibus', branch: 'sersut/ff-ksubrama/gcc_investigate'
-gem 'omnibus-software', github: 'chef/omnibus-software', branch: 'shain/ruby_windows_monster'
+gem 'omnibus-software', github: 'chef/omnibus-software'
 gem 'license_scout', github: 'chef/license_scout'
 
 # This development group is installed by default when you run `bundle install`,

omnibus/config/projects/inspec.rb

@@ -37,6 +37,8 @@ end
 build_version Inspec::VERSION
 build_iteration 1
 
+override 'ruby', version: '2.3.1'
+
 dependency 'preparation'
 
 dependency 'inspec'

omnibus/config/software/inspec.rb

@@ -20,8 +20,10 @@ require_relative '../../../lib/inspec/version.rb'
 name 'inspec'
 
 dependency 'ruby'
-dependency 'rb-readline'
+dependency 'rubygems'
 dependency 'bundler'
+dependency 'rb-readline'
+dependency 'nokogiri'
 dependency 'appbundler'
 
 license :project_license