Virtio console

Hi guys,

I have 3 bugfixes related to virtio_console test.

* 55ff7e2 adds existing fix (66e6577f724c3c4731a362ea6ca41f7d6a38ca98) to similar places
* 39f6548 is a bit nastier as it permanently disables agetty on hvc0. I'm not aware of any tests using hvc0 for login so it shouldn't matter. Anyway if there is such case it will start failing after virtio_console test is executed on SystemD guests. I filled a bug and I'm waiting for response whether SystemD behaves right ( https://bugzilla.redhat.com/show_bug.cgi?id=920648 ). Anyway for now this this fixes the problem of virtio_console test with console tests on systems with SystemD.
* 17e958a better logging