Running onos-setup-karaf clean deletes the karaf directory and any custom configs
you may have put in there. This change allow a developer to put custom configs
in the usual place ($ONOS_ROOT/tools/package/{config,etc}/) and have them copied
automatically to the local Karaf installation.
Change-Id: I9d7feabdee8f8a89930b9955de610dc821d8fdbb