Add g method (named after (s)ed's g//) to Chef::Util::FileEdit for more flexible text manipulation

chef_fileedit_g.rb

class Chef
  class Util
    class FileEdit
      public
      # Run block for matching lines, passing it matching line.
      # Replaces matching lines with value returned by the block.
      def g(regex)
        exp = Regexp.new(regex)
        new_contents = []
        contents.each do |line|
          if line =~ exp
            replacement = (yield line) || line
            new_contents << replacement
            @file_edited ||= ( line != replacement )
          else
            new_contents << line
          end
          @contents = new_contents
        end
      end
    end
  end
end