Comment 2 for bug 967916

Also note update to nova that enables version checking conditionals throughout
get_ec2_metadata and only includes the metadata if the requested version
should contain it.

When there is a difference between Amazon API implementation and documentation
I've gone with replicating the implementation. So far differences include:
- undocumented hostname introduced in 1.0, deprecated in favour of
  local-hostname
- kernel-id and ramdisk-id seem have to been implemented in 2007-12-15,
  not 2008-02-01 as documented

get_ec2_metadata has also been reordered so that data is added oldest to
newest by API version. In a future change I may attempt to add
unimplemented API versions (2011-01-01, 2012-06-01).

See https://review.openstack.org/#/c/9205/