added ExportWorker

app/workers/export_worker.rb

@@ -0,0 +1,16 @@
+require 'exporter'
+class ExportWorker
+  include Sidekiq::Worker
+
+  sidekiq_options queue: :export, retry: false
+
+  # @param user_id [Integer] the user id
+  def perform(user_id)
+    exporter = Exporter.new User.find(user_id)
+    exporter.export
+    question = Question.create(content: "Your #{APP_CONFIG['site_name']} data export is ready!  You can download it " +
+        "from the settings page under the \"Export\" tab.", author_is_anonymous: true,
+        author_name: "retrospring_exporter")
+    Inbox.create(user_id: user_id, question_id: question.id, new: true)
+  end
+end