About IdP V2 and spring versions

[Rod Widdowson]

The full gory details are in the case notes for IDP-571

Briefly:  the provided "post-registration" hook is too late in the
processing.  Bean factory processing the context happens a bit late (I
didn't investigate too closely) but might be made to work in a bludgeoning
sort of way.

I eschewed hacking the DOM, but I found a trivial method to override which
allows us to very topically remove exactly those aliases that were added for
exactly that Customer Element.

I've checked this in as 7243.  We can discuss before I make the same (or a
different) change for the other two affected places.

Rod