Remove DEBIAN_FRONTEND & move apt-get to one-line
Remove DEBIAN_FRONTEND & move apt-get to one-line

The ENV for DEBIAN_FRONTEND persists through the build. This causes issues if you ever need to connect to the running instance. 
Also the apt-get should be a one liner to help with maintain ability issues (ensuring that when curl is installed its the most up to date)
cscu/docker-teamspeak-server