Add dextrose_updater module

Be able to set DEXTROSE_YUM_REPO from .ini images files.

This avoids having to add complex logic to the dextrose-updater
logic, when different repositories must be added depending on
the XO model, and other variables.

Signed-off-by: Martin Abente Lahaye <tch@sugarlabs.org>
Set font size in gconf again

This is a required by, gtk2-based sugar-toolkit activities.

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