The test code needs to be changed to accommodate the renaming of vmlinuz to vmlinuz.efi for amd64 desktop kernels

The run-test.py needs to change to accommodate the renaming of the Ubuntu desktop kernel for amd64 images from vmlinuz to vmlinuz.efi.

The precise desktop jobs are using this and failing to extract the kernel in the tests and there fore the daily tests are failing.

An example failure is

bsdtar: casper/vmlinuz: Not found in archive
bsdtar: Error exit delayed from previous errors.
Traceback (most recent call last):
  File "/usr/bin/run-test", line 266, in <module>
    subprocess.check_call(cmd)
  File "/usr/lib/python2.7/subprocess.py", line 511, in check_call
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['unbsdtar-safelink', '-xf', '/var/lib/ubuntu-iso-testing/isos/ubuntu/precise-desktop-amd64.iso', '-C', '/tmp/precise-desktop-amd64.iso-FJmzPF', 'casper/vmlinuz', 'casper/initrd.lz']' returned non-zero exit status 1

https://jenkins.qa.ubuntu.com/view/Precise/view/ISO%20Testing%20Dashboard/job/precise-desktop-amd64_default/542/console