Refactoring/DRYing up code

[gaurijo]

This PR is for issue #50 , handling duplicate code for the .check_async() and .import_async() methods across different models.

Summary of Changes -

• Creation of a module (inside lib directory) that hosts a run_task() method. This method takes in a model and a task, and contains the code that is shared among all the models in invoking a rake task via ECS task to check each service.
• A private method, generate_command() was created to hold the logic of what the command should be, depending on which model the check is for.
• The generate_command() method takes in a model and task, and uses a case statement to assign the correct command depending on the service/model.
• Inside each model the check_async/import_async() method is replaced with a call to the Syncable module's run_task() method with the correct parameters.

module Syncable 
   def run_task(model, task)
       # code 
       command = generate_command(model, task)
       # code 
               overrides: {
            container_overrides: [
                {
                    name: config.ecs_async_task_container,
                    command: command 
                },
            ]
        },
      # code 
   end 
   private 

   def generate_command(model, task)
    case model 
      when :internet_archive 
        ['bin/rails', "books:check_internet_archive[#{task.id}]"]
      when :hathitrust 
        ['bin/rails', "books:check_hathitrust[#{task.id}]"]
      when :google
        ['bin/rails', "books:check_google[#{@inventory_key},#{task.id}]"]
      when :record_source  
        ['bin/rails', "books:import[#{task.id}]"]
      else
        "no such model"
    end
  end
end

• Each model includes the module to access the shared method.

e.g.

class Hathitrust
  include Syncable 

  #code
  def check_async(task)
    run_task(:hathitrust, task)
  end
  #code

end

• In order to load the Syncable module throughout the app, config/application.rbneeded to be updated with:

  config.autoload_paths += %W(#{config.root}/lib}

• I tested this locally just by running the different bin/rails commands (ie. bin/rails books:import) to make sure nothing broke