Allow ExplodedExporter to export directly into a target directory

The ExplodedExporter currently support

• exportExploded(parent)
• exportExploded(parent, targetName)

exportExploded(parent) automatically append archive.name to the output path.

We're currently missing a way to write directly to a given directory with out having to do a little dance like:

File target = new File("some/dir");
archive.as(ExplodedExporter.class).exportExploded(target.getParent(), target.getName());

Propose new ExplodedExport method exportExplodedInto(File target)