Update to the latest dynapath

This commit addresses two issues:

* dynapath is now org.tcrawley/dynapath - it needed a proper group-id
  to go to maven central, which was a requirement for pomegranate.

* 0.2.3 addresses an issue that allowed modification the boot
  classloader, which wreaked havoc.

I'm not sure if you are using the classloader modification
functionality, but if you are, I don't want you to get bitten by the
boot classloader modification - it is very painful to debug.