Fixed orientdb:migrate and dspace:import tasks

app/builders/learning_object_builder.rb

app/models/learning_object.rb

app/repositories/orient_db/base.rb

app/repositories/orient_db/learning_object_repository.rb

lib/orient_db/migration.rb

lib/orient_db/migrations.rb

lib/orient_db/migrations/create_collection.rb

lib/orient_db/migrations/create_comment.rb

lib/orient_db/migrations/create_learning_object.rb

lib/orient_db/migrations/create_subtopic.rb

lib/tasks/dspace.rake