Pessimize usb devices when determining boot device

Otherwise it believes that this machine is booted via floppy:

pci-0000:00:1a.0-usb-0:1.4:1.0-scsi-0:0:0:0 -> ../../sr0
pci-0000:00:1a.0-usb-0:1.4:1.0-scsi-0:0:0:1 -> ../../sde
pci-0000:00:1a.0-usb-0:1.4:1.0-scsi-0:0:0:2 -> ../../sdf
pci-0000:00:1f.2-scsi-1:0:0:0 -> ../../sda
pci-0000:00:1f.2-scsi-2:0:0:0 -> ../../sdb
pci-0000:00:1f.2-scsi-3:0:0:0 -> ../../sdc
pci-0000:00:1f.2-scsi-4:0:0:0 -> ../../sdd

Change it into a two pass approach, first ignoring usb, then going over
all devices.
DHCP assignment with multiple nics

When multiple ethernet adapters are present, a host file is created in /etc/dhcp3/hosts.d/ for each of the interfaces. Each of those files contained the same IP address.

* Added condition in update_nodes.rb to set IP address only for the boot interface
* Added condition in dhcp template to deny boot if no IP is set (see update_nodes.rb)
Fix start order

crowbar_join wants keystone and quantum, so start after it
(if running on the same host). (https://bugzilla.novell.com/847527)
add timeout 100 to first boot to ensure that network is up
Merge pull request #221 from vuntz/timeout-for-hyperv

add timeout 100 to first boot to ensure that network is up
Merge pull request #217 from dirkmueller/release/pebbles/master

Merging as this only impacts a SUSE file.
Merge pull request #196 from dirkmueller/device_order

Finally merging this, we tested this long enough.
Merge pull request #211 from ociuhandu/pull-req-release-pebbles-master-a753d22fc919b2fbf2464394bfac35589e6ab997

Fix DHCP IP address assignment when multiple nics are present [1/1]