Get rid of services from the base image we don't need.

Especially cron seems to be responsible for sometimes crashing the TeamSpeak3 client.

Dockerfile

@@ -1,5 +1,8 @@
 FROM phusion/passenger-nodejs:0.9.17
 
+# get rid of useless services
+RUN rm -r /etc/services/{cron,nginx,nginx-log-forwarder}
+
 # prepare APT with only the repositories we want
 RUN rm /etc/apt/sources.list.d/* &&\
 	add-apt-repository ppa:mc3man/trusty-media -y &&\