Add checkout name for Dockerfile

* Because in dockerhub, we cannot set the `docker build `running
  directory, we could only use `git clone` command to get the latest
  code if we put `Dockerfile` in subdirectory

* But the `git clone` will checkout the default branch only, so here
  we add a `ENV` in Dockerfile to checkout special branch or tag in
  git repo. We could change it to `V0.9.0` tag when it release.

paddle/scripts/docker/Dockerfile.cpu

 FROM ubuntu:14.04
 MAINTAINER PaddlePaddle Dev Team <paddle-dev@baidu.com>
 COPY build.sh /root/
+ENV GIT_CHECKOUT=develop
 ENV WITH_GPU=OFF
 ENV IS_DEVEL=OFF
 ENV WITH_DEMO=OFF

paddle/scripts/docker/Dockerfile.cpu-demo

 FROM ubuntu:14.04
 MAINTAINER PaddlePaddle Dev Team <paddle-dev@baidu.com>
 COPY build.sh /root/
+ENV GIT_CHECKOUT=develop
 ENV WITH_GPU=OFF
 ENV IS_DEVEL=ON
 ENV WITH_DEMO=ON

paddle/scripts/docker/Dockerfile.cpu-devel

 FROM ubuntu:14.04
 MAINTAINER PaddlePaddle Dev Team <paddle-dev@baidu.com>
 COPY build.sh /root/
+ENV GIT_CHECKOUT=develop
 ENV WITH_GPU=OFF
 ENV IS_DEVEL=ON
 ENV WITH_DEMO=OFF

paddle/scripts/docker/Dockerfile.cpu-noavx

 FROM ubuntu:14.04
 MAINTAINER PaddlePaddle Dev Team <paddle-dev@baidu.com>
 COPY build.sh /root/
+ENV GIT_CHECKOUT=develop
 ENV WITH_GPU=OFF
 ENV IS_DEVEL=OFF
 ENV WITH_DEMO=OFF

paddle/scripts/docker/Dockerfile.cpu-noavx-demo

 FROM ubuntu:14.04
 MAINTAINER PaddlePaddle Dev Team <paddle-dev@baidu.com>
 COPY build.sh /root/
+ENV GIT_CHECKOUT=develop
 ENV WITH_GPU=OFF
 ENV IS_DEVEL=ON
 ENV WITH_DEMO=ON

paddle/scripts/docker/Dockerfile.cpu-noavx-devel

 FROM ubuntu:14.04
 MAINTAINER PaddlePaddle Dev Team <paddle-dev@baidu.com>
 COPY build.sh /root/
+ENV GIT_CHECKOUT=develop
 ENV WITH_GPU=OFF
 ENV IS_DEVEL=ON
 ENV WITH_DEMO=OFF

paddle/scripts/docker/Dockerfile.gpu

 FROM nvidia/cuda:7.5-cudnn5-devel-ubuntu14.04
 MAINTAINER PaddlePaddle Dev Team <paddle-dev@baidu.com>
 COPY build.sh /root/
+ENV GIT_CHECKOUT=develop
 ENV WITH_GPU=ON
 ENV IS_DEVEL=OFF
 ENV WITH_DEMO=OFF

paddle/scripts/docker/Dockerfile.gpu-demo

 FROM nvidia/cuda:7.5-cudnn5-devel-ubuntu14.04
 MAINTAINER PaddlePaddle Dev Team <paddle-dev@baidu.com>
 COPY build.sh /root/
+ENV GIT_CHECKOUT=develop
 ENV WITH_GPU=ON
 ENV IS_DEVEL=ON
 ENV WITH_DEMO=ON

paddle/scripts/docker/Dockerfile.gpu-devel

 FROM nvidia/cuda:7.5-cudnn5-devel-ubuntu14.04
 MAINTAINER PaddlePaddle Dev Team <paddle-dev@baidu.com>
 COPY build.sh /root/
+ENV GIT_CHECKOUT=develop
 ENV WITH_GPU=ON
 ENV IS_DEVEL=ON
 ENV WITH_DEMO=OFF

paddle/scripts/docker/Dockerfile.gpu-noavx

 FROM nvidia/cuda:7.5-cudnn5-devel-ubuntu14.04
 MAINTAINER PaddlePaddle Dev Team <paddle-dev@baidu.com>
 COPY build.sh /root/
+ENV GIT_CHECKOUT=develop
 ENV WITH_GPU=ON
 ENV IS_DEVEL=OFF
 ENV WITH_DEMO=OFF

paddle/scripts/docker/Dockerfile.gpu-noavx-demo

 FROM nvidia/cuda:7.5-cudnn5-devel-ubuntu14.04
 MAINTAINER PaddlePaddle Dev Team <paddle-dev@baidu.com>
 COPY build.sh /root/
+ENV GIT_CHECKOUT=develop
 ENV WITH_GPU=ON
 ENV IS_DEVEL=ON
 ENV WITH_DEMO=ON

paddle/scripts/docker/Dockerfile.gpu-noavx-devel

 FROM nvidia/cuda:7.5-cudnn5-devel-ubuntu14.04
 MAINTAINER PaddlePaddle Dev Team <paddle-dev@baidu.com>
 COPY build.sh /root/
+ENV GIT_CHECKOUT=develop
 ENV WITH_GPU=ON
 ENV IS_DEVEL=ON
 ENV WITH_DEMO=OFF

paddle/scripts/docker/Dockerfile.m4

 FROM PADDLE_BASE_IMAGE
 MAINTAINER PaddlePaddle Dev Team <paddle-dev@baidu.com>
 COPY build.sh /root/
+ENV GIT_CHECKOUT=develop
 ENV WITH_GPU=PADDLE_WITH_GPU
 ENV IS_DEVEL=PADDLE_IS_DEVEL
 ENV WITH_DEMO=PADDLE_WITH_DEMO

paddle/scripts/docker/build.sh

@@ -23,6 +23,7 @@ fi
 cd ~
 git clone https://github.com/baidu/Paddle.git paddle
 cd paddle
+git checkout ${GIT_CHECKOUT}
 mkdir build
 cd build
 cmake .. -DWITH_DOC=OFF -DWITH_GPU=${WITH_GPU} -DWITH_SWIG_PY=ON\