delayed_job を操作するためのrakeタスクを追加しました

```
rake development:delayed_job:help     # show help
rake development:delayed_job:reload   # @development send a SIGHUP to all instances of the application
rake development:delayed_job:restart  # @development stop all instances and restart them afterwards
rake development:delayed_job:run      # @development start the application and stay on top
rake development:delayed_job:start    # @development start an instance of the application
rake development:delayed_job:status   # @development show status (PID) of application instances
rake development:delayed_job:stop     # @development stop all instances of the application
rake development:delayed_job:zap      # @development set the application to a stopped state

rake test:delayed_job:help            # show help
rake test:delayed_job:reload          # @test send a SIGHUP to all instances of the application
rake test:delayed_job:restart         # @test stop all instances and restart them afterwards
rake test:delayed_job:run             # @test start the application and stay on top
rake test:delayed_job:start           # @test start an instance of the application
rake test:delayed_job:status          # @test show status (PID) of application instances
rake test:delayed_job:stop            # @test stop all instances of the application
rake test:delayed_job:zap             # @test set the application to a stopped state
```