Merge branch 'licenses' into 'master'

app/controllers/v1/licenses_controller.rb

app/models/learning_object.rb

app/models/license.rb

app/policies/license_policy.rb

app/serializers/learning_object_obaa_serializer.rb

app/serializers/learning_object_serializer.rb

app/serializers/license_serializer.rb

config/routes.rb

db/migrate/20160516125724_create_licenses.rb

db/migrate/20160516125800_add_license_to_learning_objects.rb

db/seeds.rb

db/seeds/licenses.rb

test/controllers/v1/licenses_controller_test.rb

test/fixtures/licenses.yml

test/models/license_test.rb