S3 images can now be bootstrapped outside EC2.
However, this fix adds the requirement of a "region" setting.
At some point we could make "region" optional and fail when bootstrap-vz
is run outside EC2 and no "region" is set.
* 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
Specify the version in the manifest (system/waagent section)
Add possibility to specify waagent conf file in manifest (system/waagent section)
Update documentation to match changes
Use log_check_call instead of log_call
refactor test on dictionary key