Renaming merge_worker -> merge_exec.
Renaming merge_worker -> merge_exec.

iron-io/iron_worker_ruby_ng,iron-io/iron_worker_ruby_ng,iron-io/iron_worker_ruby_ng,iron-io/iron_worker_ruby_ng,iron-io/iron_worker_ruby_ng,iron-io/iron_worker_ruby_ng,iron-io/iron_worker_ruby_ng