Update cluster API to node 0.8; remove node 0.6-compatibility code.

The 'death' event was renamed to 'exit' in node 0.8.

We have dependencies that no longer work on node 0.6, so go ahead and
remove the node 0.6-compatibility barnacles while we're updating this.

Bug: 49599
Change-Id: I2b7119c928ed27e26181c67c6d300f526cd53801