Refactor recent client changes

I find `push` is easier to read this way. push_bulk is quite complex and adds a net-negative layer of abstraction.

lib/sidekiq/client.rb

@@ -70,7 +70,14 @@ module Sidekiq
     #   push('queue' => 'my_queue', 'class' => MyJob, 'args' => ['foo', 1, :bat => 'bar'])
     #
     def push(item)
-      push_bulk(item.merge("args" => [item["args"]])).first
+      normed = normalize_item(item)
+      payload = middleware.invoke(normed["class"], normed, normed["queue"], @redis_pool) do
+        normed
+      end
+      if payload
+        raw_push([payload])
+        payload["jid"]
+      end
     end
 
     ##
@@ -100,10 +107,11 @@ module Sidekiq
 
       normed = normalize_item(items)
       payloads = args.map.with_index { |job_args, index|
-        copy = normed.merge("args" => job_args, "jid" => jid || generate_jid)
+        copy = normed.merge("args" => job_args, "jid" => SecureRandom.hex(12))
         copy["at"] = (at.is_a?(Array) ? at[index] : at) if at
-
-        result = process_single(items["class"], copy)
+        result = middleware.invoke(copy["class"], copy, copy["queue"], @redis_pool) do
+          copy
+        end
         result || nil
       }.compact
 
@@ -225,13 +233,5 @@ module Sidekiq
         conn.lpush("queue:#{queue}", to_push)
       end
     end
-
-    def process_single(job_class, item)
-      queue = item["queue"]
-
-      middleware.invoke(job_class, item, queue, @redis_pool) do
-        item
-      end
-    end
   end
 end

lib/sidekiq/job_util.rb

@@ -40,10 +40,10 @@ module Sidekiq
 
       raise(ArgumentError, "Job must include a valid queue name") if item["queue"].nil? || item["queue"] == ""
 
+      item["jid"] ||= SecureRandom.hex(12)
       item["class"] = item["class"].to_s
       item["queue"] = item["queue"].to_s
       item["created_at"] ||= Time.now.to_f
-
       item
     end
 
@@ -61,9 +61,5 @@ module Sidekiq
     def json_safe?(item)
       JSON.parse(JSON.dump(item["args"])) == item["args"]
     end
-
-    def generate_jid
-      SecureRandom.hex(12)
-    end
   end
 end

lib/sidekiq/worker.rb

@@ -206,7 +206,6 @@ module Sidekiq
 
         # validate and normalize payload
         item = normalize_item(raw)
-        item["jid"] ||= generate_jid
         queue = item["queue"]
 
         # run client-side middleware
@@ -355,7 +354,7 @@ module Sidekiq
 
       def client_push(item) # :nodoc:
         raise ArgumentError, "Job payloads should contain no Symbols: #{item}" if item.any? { |k, v| k.is_a?(::Symbol) }
-        build_client.push_bulk(item.merge("args" => [item["args"]])).first
+        build_client.push(item)
       end
 
       def build_client # :nodoc: