Add support for cluster/OS parameters in QA

Currently there is no way to QA with (for example) an initrd because
the QA only inits the cluster with the default parameters. This makes
it impossible to QA using anything but the default parameters, which
doesn't always work.

Additionally, we add OS parameters and OS hypervisor parameters, for
completeness and for testing that these commands also work.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>