Stop publishing docker container ports to static ports

[msheiny]

Example beats_role_elasticsearch publishing ES port at 9200. Let's make this variable (whatever docker decides) and then utilize that value further down the chain and print it out to the local user.

Reasoning to do this is because in the process of writing this role alongside the rest of the ELK stack... I've been hitting a bunch of port conflicts locally between multiple instances of ELK components running in different containers 😖