Closes #19
rebar3 is already installed in image.
This commit adds a .travis.yaml file in the root folder that will trigger tests for the examples in the advanced_examples folder. The tests are based on the .travis.yaml files that existed in the branches that the examples were taken from.
This commit copies Siri Hansen's (@sirihansen) Logstash example from: https://github.com/erlang/docker-erlang-example/tree/logstash