add support for tap devices

- support tap devices
- use -netdev instead of -net
remove installstep.pm, now in distro specific repos
Merge pull request #61 from lnussel/master

remove installstep.pm, now in distro specific repos
networking documentation
fix codestyle
support virtio-scsi as hdd model

- when virtio-scsi is set as hdd model, create scsi controller and
set drives as scsi-hd
- this allows to have /dev/sd* devices in QEMU guest
Merge pull request #63 from aaannz/virtio-scsi_support

support virtio-scsi as hdd model
installstep is gone
Merge pull request #62 from aaannz/tap_support

support for TAP devices
write crash file in case of trouble in mgmt thread

also refactor code
Merge pull request #64 from lnussel/master

write crash file in case of trouble in mgmt thread
add -no-shutdown to qemu params

don't quit qemu if the vm shuts down as that could kill os-autoinst
unexpectedly. Let os-autoinst quit qemu explicitly instead.
Merge pull request #65 from lnussel/master

add -no-shutdown to qemu params
record wait_serial also in results
fix ensure_installed for SLE
Merge pull request #66 from lnussel/master

record wait_serial also in results
add flag norollback to be used by shutdown
Merge pull request #67 from lnussel/master

add flag norollback to be used by shutdown