It allows provide to set some defaults.

Also use directly parameters instead of json.

Json would require in-code parsing, which would lead to complex recipes.

It will request all required services. json is in parameter dict.

More: software.cfg does not have to specify a lot of parts, as main template
is driving the choice process.

haproxy checks for site-id/getId response, but the site does not exists yet, so
it disallows to access the site.

In case of instantiating erp5 software type the later buildout will fail with
correct error message. But template is generated *always*, even in cases when
some data are not available yet.

Thanks to this all goodies provided by GenericBaseRecipe are available to
"connected" recipes.

Also drop another legacy, as it was migrated to profile based idea.