saner defaults for template

The current defaults for logos and similar information in the variables.php.template file make for broken images in the default install. It would be better to have those commented out than to have a sample code that yields broken images.

This is a port of [this pull request](https://github.com/leblanc-simon/OpenSondage/pull/55) to Simon Leblanc's repository, which seems now abandoned.

I also add patches to remove framasoft-specific code from other parts of the software.

(rerolled out of my master branch from #20).