fix request_id instrumentation to follow Build & Packaging standard

Author: hone

lib/language_pack/instrument.rb

@@ -7,7 +7,7 @@
 module LanguagePack
   module Instrument
     def self.bench_msg(message, level = 0, start_time, end_time, duration, build_id, buildpack_version)
-      out.puts "measure.#{message}.start=#{start_time} measure.#{message}.end=#{end_time} measure.#{message}.duration=#{duration} measure.#{message}.level=#{level} measure.#{message}.build_id=#{build_id} measure.#{message}.request_id=#{request_id} measure.#{message}.buildpack_version=#{buildpack_version} measure.#{message}.buildpack=#{buildpack_name} "
+      out.puts "measure.#{message}.start=#{start_time} measure.#{message}.end=#{end_time} measure.#{message}.duration=#{duration} measure.#{message}.level=#{level} measure.#{message}.build_id=#{build_id} request_id=#{request_id} measure.#{message}.buildpack_version=#{buildpack_version} measure.#{message}.buildpack=#{buildpack_name} "
       out.send :flush
     end