Config reorg

[Cantor, Scott]

I did some reorganizing of the configuration imports so that now the
system files that configure various components directly import the user
versions of those files, instead of having a user-visible global.xml doing
the imports.

This eliminates global.xml, and I think we need that gone to avoid having
a file in conf/ that might have to be modified to handle new features
introduced in minor updates. This way we can add imports of new files in
conf/ to global-system.xml or its imports, which we control and replace on
upgrades.

I'm heavily using relative paths with parent notation to make all this
work, but that seems to work for both classpath and file resources, so I
think it's safe to count on that.

-- Scott