XenAPI: Cirros images must always boot as PV.

The default for VHD disk-types is PV, which is why booting from a
server works.  However, creating a volume from the image needs to
pass this parameter on to the volume.  Note that
Id673158442fde27e8d468ca412c9bd557a886e6b is also required to fix
bug 1294069

Change-Id: I7ea1d85d6082787ac4551f78300a04bf59074261
Partial-Bug: 1294069
Fix incorrect tempest config groups

This commit fixes a couple of tempest config options that were being
iniset to the wrong config group. This wasn't caught in the gate
because the default behaviors matched.

Change-Id: I273db85ba310faa1ba7662a42f951a1ee97b431b
Skip child process kills in stack.sh exit trap

Logs are still being cut off in certain circumstances, almost certainly
because the awk process handling the output for verbose logging to a file
dies/is killed early.

Don't kill child processes in the EXIT trap function in this specific case.

Change-Id: I89600b61d59f87e93ff959710d0169e49d2c9845
Merge "Skip child process kills in stack.sh exit trap"
Merge "Fix incorrect tempest config groups"
Merge "XenAPI: Cirros images must always boot as PV."