Some people want the security team-supported 3.2 kernel, while others
want the better performance of the backports kernel. Both flavors are
currently provided in the Google Compute Engine debian-cloud project.
Also add OpenSSH to the backports flavor, for parity with the current
GCE backports image based on build-debian-cloud. This backport is
included for performance reasons, in line with the purpose of that image
flavor, and as discussed on the debian-cloud list.
* force kpartx to use synchronous mode, removing sleep(10)
* get image configuration, use it during tarball creation and registration
* add (non-working, path problems) image registration
* add cleaning of image from Google keys and repositories
* add NTP server address in manifest
* add preference for backport kernels in manifest
* disable IPv6
* correctly set host name
