don't use sudo as Docker RUN commands run as root

Author: hturner

Dockerfile

@@ -17,7 +17,7 @@ RUN sed -i.bak "/^#.*deb-src.*universe$/s/^# //g" /etc/apt/sources.list \
       software-properties-common \
       subversion \
     && add-apt-repository --enable-source --yes "ppa:marutter/rrutter4.0" \
-    && wget -qO- https://cloud.r-project.org/bin/linux/ubuntu/marutter_pubkey.asc | sudo tee -a /etc/apt/trusted.gpg.d/cran_ubuntu_key.asc \
+    && wget -qO- https://cloud.r-project.org/bin/linux/ubuntu/marutter_pubkey.asc | tee -a /etc/apt/trusted.gpg.d/cran_ubuntu_key.asc \
     && apt -y build-dep r-base-dev \
     && apt -y install r-base-dev \
     && Rscript -e "install.packages(c('languageserver', 'httpgd'), \