recipe/generic_cloudooo: Allow to set up scripting.

The option "ooo_enable_scripting" can now be set up in the
generic.cloudooo recipe.
This option allows the Cloudooo server to execute user scripts to edit
the documents before they are saved
(see cloudooo@a09d87af3f8bf222cd7d37d814b94ed7a907e2b4).

See merge request nexedi/slapos!1628