doc update

doc/install.rst

@@ -97,12 +97,12 @@ Install the dependencies for library first with::
 
   $ sudo usermod -a -G spi,gpio pi
   $ sudo apt-get install python-dev python-pip libfreetype6-dev libjpeg-dev
-  $ sudo -i pip install --upgrade pip
   $ sudo apt-get purge python-pip
+  $ sudo -i pip install --upgrade pip setuptools
 
 .. warning:: The default pip bundled with apt on Raspbian is really old, and can 
    cause components to not be installed properly. Please ensure that **pip 9.0.1** 
-   is installed prior to continuing::
+   or newer is installed prior to continuing::
    
       $ pip --version
       pip 9.0.1 from /usr/local/lib/python2.7/dist-packages (python 2.7)