Refactor package names to match module names

[Tom Zeller]

>> + spring-extensions : n.s.ext.spring -> n.s.spring.extensions
>
> This one I care about a bit because we have released a 1.0.0 of that.  Obviously this would be a breaking change for anyone dependent on it and would require a 2.0.0.  But I think we were already in that situation?
>
> As a general thing, I'd say any breaking changes are best done earlier rather than later.

I actually do not want to refactor spring-extensions, so any reason
not to I will follow. However, if were are going to cut a release then
this is the time to refactor, as you say. I still need to review
versioning of spring-extensions and java-support, fyi.