[ruby/rack] Detect workers for Iodine

+------------------------+---------+------+------+-----+-----+-------+--------------+
|             branch_name|plaintext|update|  json|   db|query|fortune|weighted_score|
+------------------------+---------+------+------+-----+-----+-------+--------------+
|                  master|   259715| 20822|230636|54927|21659|  49761|          2465|
|rack/iodine-set-workers2|   259700| 20056|265800|98671|60333|  50916|          3370|
+------------------------+---------+------+------+-----+-----+-------+--------------+

frameworks/Ruby/rack/rack-iodine.dockerfile

@@ -19,4 +19,4 @@ COPY . .
 
 EXPOSE 8080
 
-CMD bundle exec iodine -p 8080
+CMD bundle exec iodine -p 8080 -w $(ruby config/auto_tune.rb | grep -Eo '[0-9]+' | head -n 1)