add an Windows installer option to dump installation log to a file

Currently, the following command does not work:

start /wait nuxeo-7.10-setup.exe /S /D=d:\Nuxeo /O=c:\myLog.log

Looking at the installer configuration it seems there is no such option:
http://nsis.sourceforge.net/Which_command_line_parameters_can_be_used_to_configure_installers

But the MakeNSIS command has one:
http://nsis.sourceforge.net/Docs/Chapter3.html#usagereference:

After googling it seems possible to do so and dump the logs to a file by adding a plugin during the installer build:
http://nsis.sourceforge.net/NSISLog_plug-in

Looking at the current installer build, the installer already uses at least one plugin so that may be compatible:
https://github.com/nuxeo/nuxeo-packaging-windows
https://qa.nuxeo.org/jenkins/view/PPLNightlyBuild/job/Deploy/job/IT-nuxeo-master-build-windows/

As a side note, it might be a good idea to upgrade at the same time the NSIS version (currently 2.46 and latest is 3.01).