Make puma stays in foreground

Dockerfile

@@ -26,6 +26,7 @@ RUN addgroup --gid 1000 discourse \
  && mkdir -p ./tmp/sockets \
  && git clone --branch v${DISCOURSE_VERSION} https://github.com/discourse/discourse.git \
  && cd ./discourse \
+ && sed -i 's/daemonize true/daemonize false/g' ./config/puma.rb \
  && chown -R discourse:discourse . \
  && git remote set-branches --add origin tests-passed \
  && curl --silent --location https://deb.nodesource.com/setup_8.x | bash - \