Update Dockerfile

removed unnecessary sudo

Dockerfile

@@ -4,7 +4,7 @@ MAINTAINER Carlos A. Gomes <carlos.algms@gmail.com>
 # Add Node.js repo
 RUN \
 curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add - \
-echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list \
+echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list \
 curl -sL https://deb.nodesource.com/setup_8.x | bash - \
  && apt-get install --no-install-recommends -y \  
   nodejs \