Merge pull request #398 from JiabinYang/fix/1.1_dev

fix python35 on ubt18.04

doc/fluid/beginners_guide/install/compile/compile_Ubuntu.md

@@ -136,7 +136,7 @@
 
 
 			For Python2: apt install python-pip
-			For Python3: apt install curl && curl https://bootstrap.pypa.io/get-pip.py -o - | python3.5 && easy_install pip
+			For Python3: apt-get udpate && apt-get install -y software-properties-common && add-apt-repository ppa:deadsnakes/ppa && apt install curl && curl https://bootstrap.pypa.io/get-pip.py -o - | python3.5 && easy_install pip
 
 
 	* c. 安装虚环境`virtualenv`以及`virtualenvwrapper`并创建名为`paddle-venv`的虚环境：

doc/fluid/beginners_guide/install/install_Ubuntu.md

@@ -51,7 +51,8 @@ Python2.7：
 
 Python3.5（该指令适用于本机未安装python2的用户，否则，请卸载python2之后再使用本指令）：        
 
-	apt-get install -y curl python3.5 python3.5-dev wget vim git && curl https://bootstrap.pypa.io/get-pip.py -o - | python3.5 && easy_install pip && pip3 install paddlepaddle
+	
+	apt-get udpate && apt-get install -y software-properties-common && add-apt-repository ppa:deadsnakes/ppa && apt-get install -y curl python3.5 python3.5-dev wget vim git && curl https://bootstrap.pypa.io/get-pip.py -o - | python3.5 && easy_install pip && pip3 install paddlepaddle
 	
 
 首先，我们使用以下指令来**检测本机的环境**是否适合安装PaddlePaddle：
@@ -90,6 +91,8 @@ Python3.5（该指令适用于本机未安装python2的用户，否则，请卸
 			i. `wget http://developer.download.nvidia.com/compute/machine-learning/repos/ubuntu1604/x86_64/nvidia-machine-learning-repo-ubuntu1604_1.0.0-1_amd64.deb`     
 			ii.  `dpkg -i nvidia-machine-learning-repo-ubuntu1604_1.0.0-1_amd64.deb`       	 	          
 			iii. `sudo apt-get install -y libnccl2=2.2.13-1+cuda9.0 libnccl-dev=2.2.13-1+cuda9.0` 
+
+
 	> 2. 如果您不规定pypi包版本号，我们默认为您提供支持Cuda 9/cuDNN v7的PaddlePaddle版本。