Explicitly set USER root in every Dockerfile

Contribution (c) Copyright IBM Corp. 2015

all-spark-notebook/Dockerfile

@@ -3,6 +3,8 @@ FROM jupyter/minimal-notebook
 
 MAINTAINER Jupyter Project <jupyter@googlegroups.com>
 
+USER root
+
 # Spark dependencies
 ENV APACHE_SPARK_VERSION 1.4.1
 RUN apt-get -y update && \

datascience-notebook/Dockerfile

@@ -2,6 +2,8 @@ FROM jupyter/minimal-notebook
 
 MAINTAINER Jupyter Project <jupyter@googlegroups.com>
 
+USER root
+
 # R pre-requisites
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \

minimal-notebook/Dockerfile

@@ -3,6 +3,8 @@ FROM debian:jessie
 
 MAINTAINER Jupyter Project <jupyter@googlegroups.com>
 
+USER root
+
 # Install all OS dependencies for fully functional notebook server
 ENV DEBIAN_FRONTEND noninteractive
 RUN apt-get update && apt-get install -yq --no-install-recommends \

pyspark-notebook/Dockerfile

@@ -3,6 +3,8 @@ FROM jupyter/minimal-notebook
 
 MAINTAINER Jupyter Project <jupyter@googlegroups.com>
 
+USER root
+
 # Spark dependencies
 ENV APACHE_SPARK_VERSION 1.4.1
 RUN apt-get -y update && \

r-notebook/Dockerfile

@@ -3,6 +3,8 @@ FROM jupyter/minimal-notebook
 
 MAINTAINER Jupyter Project <jupyter@googlegroups.com>
 
+USER root
+
 # R pre-requisites
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \

scipy-notebook/Dockerfile

@@ -3,6 +3,8 @@ FROM jupyter/minimal-notebook
 
 MAINTAINER Jupyter Project <jupyter@googlegroups.com>
 
+USER root
+
 # Install Python 3 packages
 RUN conda install --yes \
     'ipywidgets=4.0*' \