Adiing Kafka and rabbitMQ

[flefevre]

In certain application it could be usefull to use both kafka and rabbitmq for different needs [1,2]
Baddly when running the rabbitmq generation command, i got:

`[fl218080@is233628 j5rk]$ yo jhipster-spring-cloud-stream

           ████    ████        
           ████    ████        
           ████    ████        
           ████    ████        
           ████████████████████
           ████████████████████
           ████████████    ████
           ████████████    ████
           ████████████████████
           ████████████████████

Welcome to the JHipster spring-cloud-stream generator! v0.0.2

Error jhipster-spring-cloud-stream

ERROR! You already have Kafka in your project, no need to add RabbitMQ.`

Would it be possible to remove this hook?

[pascalgrimaud]

of course, it can be done.
Would you like to contribute and do a PR ?