ruby config detection no longer works in ruby version 2.2

[thoughtcroft]

Using ::Config for detecting the various config settings which are populated into node[:languages][:ruby] has been deprecated since 1.9.3. In ruby 2.2.0, this has been removed. The recommended way is to use RbConfig, which works.

ruby -e "require 'rbconfig'; puts %Q(bindir=#{::Config::CONFIG['bindir']})"
-e:1:in `<main>': uninitialized constant Config (NameError)

ruby -e "require 'rbconfig'; puts %Q(bindir=#{::RbConfig::CONFIG['bindir']})"
bindir=/Users/warrenbain/.rbenv/versions/2.2.0/bin

[thoughtcroft]

#454