Merge pull request #305 from PaddlePaddle/docker_book

fix file exists bug

.tools/build_docker.sh

@@ -74,8 +74,6 @@ RUN curl https://storage.googleapis.com/golang/go1.8.linux-amd64.tar.gz -o go1.8
     tar -zxvf go1.8.linux-amd64.tar.gz -C /usr/local/ && \
     rm go1.8.linux-amd64.tar.gz
 
-RUN ln -s /usr/local/go/bin/go /usr/local/bin/go
-
 #convert md to ipynb
 RUN /bin/bash /book/.tools/convert-markdown-into-ipynb-and-test.sh