compute nodes don't come up correctly after reboot

Currently, after a reboot of a compute node, these things are wrong:

- nova-network isn't running, but starts up fine with `service nova-network restart`
- nova-compute doesn't start at boot, and doesn't restart instances:
```
OSError: [Errno 2] No such file or directory: '/var/run/nova/instances'
```

We need to move nova state dir to a stable directory, such as /var/lib/nova.

Before closing this, verify:
1. nova-network and nova-compute are running happily at boot.
2. `nova-manage service list` looks good
3. running instances are restarted automatically