HPCloud Precise image has a new name.

HPCloud deprecated the Precise image we were using in nodepool. This
means they renamed it which broke all of our nodepool precise image
builds in hpcloud. They did not replace the image instead the indication
seems to be that users are expected to use partner images.

We are told the Precise partner images are provided by canonical and are
safe to use. This means that we can in theory also use the Trusty
partner image but that is a change for another day.

Change-Id: I27f9d1e5bfa261610d76edaf8b56df74705cffdd