otherwise buggy slapos.core-1.0 will be used if exists.

This work has nothing to do in erp5-component branch, and is preventing it
from being merged to erp5 banch more often.
Conflicts because of non-reverted
6d1a9805 have been resolved to that its
intent is preserved with non-cluster ERP5 SR.

This reverts commit 77976a14.
This reverts commit 7aa1d92c.
This reverts commit 80062015.
This reverts commit 36ed58f2.
This reverts commit 1fe3f466.
This reverts commit 7731726a.
This reverts commit eb2016c4.

In preparation for better ERP5 clusterisation.

It is not used in xwiki and lamp, does not work out of the box in erp5, and
prevents erp5 from moving further toward IPv6 support.
Do not drop its component SR and recipe just yet, as it might find some
use in the near future.

Kept backward compatibility about "production" software_type.

All ERP5 profile is now in a single place.
Moreover, use slapos.cfg stack.

Also, stop referencing reference implicitly pulled parts.