Websphere liberty Maven plugin allows you to package a liberty server assembly and deploy it to repo Manager like Nexus:
https://github.com/WASdev/ci.maven#liberty-assembly

It would be good if the Liberty Arquillian container could be configured to download and use this liberty assembly.
https://github.com/arquillian/arquillian-container-was/tree/master/wlp-managed-8.5

This mean each environment the tests run on would'nt need to be pre-installed with a Liberty server.