upgading aether

I thought updating aether might help with leinengen performance. It doesn't appear to, but I'm not certain yet.

The package changes break client apps like leiningen because they're catching specific org.sonatype Exceptions. I thought I'd send you this pull request anyway because the work might come in handy some day. So, take it for what it is.

I used the Aether Demo to figure out what changes needed to be made. I've annotated a couple of spots that I didn't understand the consequences of what I was doing.

http://git.eclipse.org/c/aether/aether-demo.git/tree/