Patch R package install user issues

-The following patch addresses issue #489
(https://github.com/jupyter/docker-stacks/issues/489)

all-spark-notebook/Dockerfile

@@ -8,6 +8,7 @@ USER root
 
 # RSpark config
 ENV R_LIBS_USER $SPARK_HOME/R/lib
+RUN fix-permissions $R_LIBS_USER
 
 # R pre-requisites
 RUN apt-get update && \