clean tests and add score calculator service test

Gemfile

app/services/score_calculator_service.rb

test/controllers/feedback_controller_test.rb

test/controllers/learning_object/chunks_controller_test.rb

test/fixtures/bookmarks.yml

test/fixtures/carousels.yml

test/fixtures/collection_items.yml

test/fixtures/collections.yml

test/fixtures/complaint_reasons.yml

test/fixtures/complaints.yml

test/fixtures/downloads.yml

test/fixtures/feedback_ratings.yml

test/fixtures/feedbacks.yml

test/fixtures/follows.yml

test/fixtures/institutions.yml

test/fixtures/learning_object/attachments.yml

test/fixtures/learning_objects.yml

test/fixtures/likes.yml

test/fixtures/metadata.yml

test/fixtures/rates.yml