Switch to media-base-system image, remove default command

Dockerfile

-FROM ubuntu:xenial
+FROM motionbank/media-base-system:latest
 MAINTAINER Motion Bank
 
-# Install NodeJS 9
-
-RUN apt-get update && apt-get install -y curl build-essential
-RUN curl -sL https://deb.nodesource.com/setup_9.x | bash -
-RUN apt-get install -y nodejs
-RUN npm i -g npm
-
-# Install FFmpeg & Graphicsmagick
-
-RUN apt-get update && apt-get install -y software-properties-common && add-apt-repository ppa:jonathonf/ffmpeg-4
-RUN apt-get update && apt-get install -y ffmpeg graphicsmagick
-RUN which ffmpeg && which ffprobe && which gm
-RUN ffmpeg -version && ffprobe -version
-
-# Install LTC tools
-
-RUN apt-get update && apt-get install -y git pkg-config libjack-dev libsndfile-dev libltc11 libltc-dev
-RUN git clone https://github.com/x42/ltc-tools.git
-RUN cd ltc-tools && make all && make install && cd .. && rm -r ltc-tools
-
-# Cleanup
-
-RUN apt-get remove -y software-properties-common curl git pkg-config && apt-get autoremove -y && apt-get clean
-
 # Setup app
 
 WORKDIR /app
 COPY . .
 RUN rm -rf node_modules
 RUN npm install --production
-EXPOSE 4040
-CMD ["node", "src"]