add missing foreign keys from migrations

db/migrate/20160124114036_create_languages.rb

db/migrate/20160124145100_create_object_types.rb

db/migrate/20160125120915_create_learning_objects.rb

db/migrate/20160125124125_institutions_users.rb

db/migrate/20160125124500_create_complaint_reasons.rb

db/migrate/20160125124508_create_complaints.rb

db/migrate/20160125132447_create_bookmarks.rb

db/migrate/20160127135807_create_reviews.rb

db/migrate/20160128115107_create_views.rb

db/migrate/20160128115428_create_downloads.rb

db/migrate/20160128115555_create_likes.rb

db/migrate/20160128115721_create_shares.rb

db/migrate/20160128123028_create_review_ratings.rb

db/migrate/20160128123901_create_follows.rb

db/migrate/20160128125336_create_collection_items.rb

db/migrate/20160130191533_create_topic_relationships.rb

...te/20160217114745_remove_language_from_learning_object.rb

...20160218121149_add_column_language_to_learning_objects.rb

...23123901_change_column_object_type_of_learning_objects.rb

...rate/20160229164600_change_users_add_score_foreign_key.rb