Use nova CLI for network creation

Prefer the "nova" tool over  "nova-manage" for network creation.

Fixes bug 1167657

Patchset adds missing <title> element to Creating Custom Images.
Patchset corrects <productnumber> for <prompt> in Lay of the Land.

Change-Id: Id5d229f530203f361d71ae2c0cd8385297ee3829
Merge "Use nova CLI for network creation"