CacheWarmer and SlackIntegration push to non-existing docker registry

[Desarc]

The publish scripts for CacheWarmer and SlackIntegration attempt to push docker images to a non-existing docker registry. It would probably be better if the registry address was parametrized.

https://github.com/Sankra/MediaServer/blob/master/SideCars/CacheWarmer/publish.sh
https://github.com/Sankra/MediaServer/blob/master/SideCars/SlackIntegration/publish.sh