Reduce Docker Image size
Reduce Docker Image size

* Set up all ENV variables in a single layer
* use `--no-install-recommends` to avoid library bloat
* clean up apt within each layer.
* only install production libs with npm, and remember to delete the cache.

Fiware/security.Idm,Fiware/security.Idm,ging/fiware-idm,ging/fiware-idm,ging/fiware-idm,Fiware/security.Idm