Move to a newer version of Xen for our standard image
This will probably be 4.5, but I think 4.6 is out now as well. At any rate, it will be whatever is standard with Ubuntu 16. The steps:
- Make sure it works as a vnode host. This is the highest priority.
- Make sure it works in elabinelab as a boss/ops host.
- Convert the shared node hosts in Emulab.
Down the road:
- Convert the CloudLab control nodes to use it.
Out in the weeds:
- Convert the geni racks to use it.