[SYSTEMS] Update travis.yml to install rabbitmq-server in latests ubuntu images
[SYSTEMS] Update travis.yml to install rabbitmq-server in latests ubuntu
images

- Latests golang images are using Ubuntu Xenial and it is necessary to
install rabbitmq-server package as an addon. For more information:
https://docs.travis-ci.com/user/database-setup/#rabbitmq

aleasoluciones/simpleamqp