libvirt_xml: update CPUXML and capabilityXML

Commit 393d19fa update class CPUXML without update related methods
of it, so fix it. And create a new func to do feature number check.

Signed-off-by: Yanbing Du <ydu@redhat.com>
qemu_storage: Fix qemu-img help text.

Newer version of qemu-img won't return help text without "-h" option.

Signed-off-by: Hao Liu <hliu@redhat.com>
Merge pull request #1822 from Hao-Liu/fix_qemu_img

qemu_storage: Fix qemu-img help text.
Merge pull request #1805 from will-Do/vm_cpu_xml

libvirt_xml: update CPUXML and capabilityXML
virt.cfg: adjust Ubuntu preseed grub cmdline

When booting into single-user mode only the first console in the
list will actually show a prompt. This lead to issues with a few of
the qemu tests. Switch the order so the proper terminal shows a prompt
in single user mode.

Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>