Merge branch 'delete_objects' into 'master'

app/controllers/concerns/taggable_controller.rb

app/controllers/v1/collections_controller.rb

app/controllers/v1/learning_objects_controller.rb

app/models/collection.rb

app/models/concerns/metadatable.rb

app/policies/collection_policy.rb

config/routes.rb

test/controllers/v1/collections_controller_test.rb

test/controllers/v1/learning_objects_controller_test.rb

test/fixtures/collection_item.yml

test/fixtures/collections.yml

test/fixtures/educational_stages.yml

test/fixtures/subjects.yml