Update HPCloud Precise image name

The image name we were using with nodepool for hpcloud precise images is
no longer valid. Does not show up in a `nova image-list` and nodepool
image builds fail. Use the most recent non deprecated Precise image
available to us according to `nova image-list`.

Change-Id: I65a37c70823f8a5d6d08af36f3c7cd1e3ab1021f
Merge "Update HPCloud Precise image name"