Added workaround for backported kernels on Ubuntu 12.04

I added a workaround for Ubuntu 12.04 using kernels backported from
newer releases that may not automatically load the KVM modules for
hardware acceleration of VMs when the system boots. Since this
issue affects compute nodes running on both bare metal and
hypervisors, I changed the step to check for nested hardware
acceleration support to check for general hardware acceleration
support.

Change-Id: Ifb3990123ffdeb40183c9f4a332dc06b1e60322e
Closes-Bug: #1313975
Merge "Added workaround for backported kernels on Ubuntu 12.04"