安装命令：
$ sudo pip install https://storage.googleapis.com/tensorflow/mac/tensorflow-0.5.0-py2-none-any.whl
报错：
ERROR: matplotlib 1.3.1 requires nose, which is not installed.
ERROR: matplotlib 1.3.1 requires tornado, which is not installed.
Installing collected packages: numpy, six, tensorflow
Found existing installation: numpy 1.8.0rc1
ERROR: Cannot uninstall 'numpy'. It is a distutils installed project and thus we cannot accurately determine which files belong to it which would lead to only a partial uninstall.
解决：
sudo easy_install nose
sudo easy_install tornado
强制安装高版本：sudo pip install numpy --ignore-installed numpy
six强制安装高版本：sudo pip install six --upgrade --ignore-installed six
