Make hypervisor_version an int in fakeVirt driver

This is a follow up to 9e770e62135fe9c2c8ac0121a5a79245b25a7847, which
missed the change in a duplicate copy of host_status.

Add regression test to test_virt_drivers.

This requires changes to the API samples, because they were wrong. virt
drivers use convert_version_to_int which converts a version string to a
4 digit number ("1.0" becomes to 1000)

Change-Id: I28ce23509e3c9feae183a49a8fc5bf3c7c601295
Closes-Bug: #1285035
Merge "Make hypervisor_version an int in fakeVirt driver"