Removed system-config-services: we save about 130MB. We never used the app since it requires an X server (we don't have one) and also docker containers don't run services as normal distros.
Bumped wait for elastic to 25 seconds. More containers -> more time to start. Also on Mac OS X boot2docker adds its own delay, thus hiding the problem.
Fixed nexus to run as nexus user and in foreground.