We currently have keys like "ComputePostOs-volumes_boot" for providers
using boot-from-volume and other various "os-" keys depending on the
provider. Normalise all these to regular CamelCase. A basic
test-case is added.
Additionally add some documentation on the API call stats, pointing
out they reflect internal details so are subject to change. A release
note is added for the updated stats.
Change-Id: If8398906a5a7ad3d96e985263b0c841e5dcaf7b5
Ian Wienand