simplify windows installation

unique procedure for windows 32bits and windows 64bits
the approprite downloaded file is automatically chosen based on the type of the user's OS: 
- python-3.4.1.msi` for win32bits
- python-3.4.1.amd.msi` for win64bits

Author: alaindomissy

part-0.ipynb

@@ -48,10 +48,10 @@
      "source": [
       "Please go to this website page https://www.python.org/downloads/ to download the Python installer:\n",
       "- click on the `Download Python 3.4.1` button (a yellow button on left side of screen),\n",
-      "- this will download the Windows x86-64 MSI installer msi file `python-3.4.1.msi` and save it to your pc,\n",
+      "- this will start the download of the appropriate Windows MSI installer 
+      "- accept the default download filename: `python-3.4.1.msi`(win32bits) or`python-3.4.1.amd.msi`(win64bits) 
+      "- save the MSI Installer file to your pc,\n",
       "- double click the downloaded file to open it and run the installer 
-      "This pocedure will differ very slightly if you are running a 64bits version of Windows: 
-      "- the button will download the Windows x86 MSI installer msi file `python-3.4.1.msi` 
        ]
     },
     {