[MERGE] loading/post_load hook: the code is consolidated in one place.

The post-load hook is called whenever a module is loaded, be it via the --load
option or via regular module installation. This is mostly for backward compatibility:
we might require an explicit --load for such server-wide modules.

bzr revid: vmt@openerp.com-20120209154800-2t11mtpf33r1bcig