Set missing gsettings overrides

Previously, these were set in OOB, but since the migration
to gsettings (from gconf) these script have not been updated.

Also, checked that these values are effectively taken from
gsettings (through Gio.settings API) in Sugar source.

Signed-off-by: Martin Abente Lahaye <tch@sugarlabs.org>
Release olpc-au-configs 0.102-2

Signed-off-by: Martin Abente Lahaye <tch@sugarlabs.org>