Impl package naming

[Tom Zeller]

> If I'm willing to do the work and clean up the
> bean files, should I do that, maybe this weekend?
>
> I have a preference for the OpenSAML naming, as it takes a package of APIs
> and adds impl to the end, which is kind of what you'd expect IMHO.

Okay with me.

After a quick look, I see that most packages in *-impl modules end
with the ".impl" suffix, but not all. Maybe they should.