Merge branch 'master' into search-api

.gitlab-ci.yml

Gemfile

Gemfile.lock

app/controllers/concerns/sociable_controller.rb

app/controllers/v1/packages_controller.rb

app/models/learning_object.rb

app/models/learning_object/attachment.rb

app/policies/learning_object_policy.rb

app/services/attachment_cache_service.rb

app/services/package_service.rb

app/services/package_service/generator.rb

app/services/package_service/link.rb

app/services/sanitization_service.rb

app/workers/attachment_cache_worker.rb

app/workers/package_worker.rb

config/routes.rb

config/sidekiq.yml