Add ssh requirement to doc.
Add an apt-get update before even fireball.

Fireball's dependencies can't be installed if the package
cache is out of date, causing failures on spanking-new machines.
Correctly set vnc_proxyclient_address:

This is used for the vnc console, and was set
to localhost.

This worked on an all-in-one installation, but must
be set to each respective compute node's ip in a multi-node
installation.