message: Fix mac installation documentation error
  This fix tries to address 17614 where installation
  for python 2 was incorrectly pointing to python3.
  The error was fixed by but later it has been overridden by
  This fix fixes 17614.
diff: @@ -118,8 +118,8 @@ Take the following steps to install TensorFlow with Virtualenv:
  Python 2.7, the command to install
  TensorFlow in the active Virtualenv is as follows:
  - <pre> $ <b>pip3 install --upgrade \
  - https://storage.googleapis.com/tensorflow/mac/cpu/tensorflow-1.6.0-py3-none-any.whl</b></pre>
  + <pre> $ <b>pip install --upgrade \
  + https://storage.googleapis.com/tensorflow/mac/cpu/tensorflow-1.6.0-py2-none-any.whl</b></pre>
  If you encounter installation problems, see
  [Common Installation Problems](#common-installation-problems).
  @@ -241,8 +241,8 @@ take the following steps:
  you are installing TensorFlow for Mac OS and Python 2.7
  issue the following command:
  - <pre> $ <b>sudo pip3 install --upgrade \
  - https://storage.googleapis.com/tensorflow/mac/cpu/tensorflow-1.6.0-py3-none-any.whl</b> </pre>
  + <pre> $ <b>sudo pip install --upgrade \
  + https://storage.googleapis.com/tensorflow/mac/cpu/tensorflow-1.6.0-py2-none-any.whl</b> </pre>
  If the preceding command fails, see
  [installation problems](#common-installation-problems).
  