Import discovery-ironic element from upstream DIB review

Imported patchset 11 of https://review.openstack.org/#/c/107672/
Enable building of discovery-ironic ramdisk in instack-build-images
Updated discovery-ironic with fixes after Gerrit review

Imported patchset 1 of https://review.openstack.org/#/c/122151/
Load discovery image into Glance
Checkout dib-utils in addition to DIB from instack-virt-setup
Add comment about swift $LKG
use ironic driver and scheduler from nova
Use wait_for_hypervisor_stats instead of arbitrary sleep
Don't install diskimage-builder from fedora in utility image
Add and use an element to install the updated dib-utils from koji
Update $LKG
Don't use dib-run-parts-update on undercloud for now
Only run this if not using Delorean
move this to pre-install.d
install pip for this fix
fix typo
Use new koji build
Adds a discovery-dhcp element

This element adds a systemd service that spawns a dnsmasq process.
TODO: add configuration - interface and dhcp alloc. range.

This dnsmasq process is intended to serve only new and undiscovered
machines. Already enrolled hardware continues to be served by the
neutron-dhcp-agent spawned dnsmasq process(es) (and this/ese is/are
already explicitly told not to answer calls from unknown machines).

The element uses iptables to block dhcp/bootp requests from already
enrolled hardware (by querying ironic), in pretty much exactly the
same way as the older bm-dnsmasq element, with a cronjob setup to
periodically update the chain (to include for example recently
discovered machines).

One drawback of this approach is the limit with which the MAC
filter can be invoked by cron (x>=1minute integer value). An
alternative is to have a bash script managed by the systemd service
that loops forever (and updates every x seconds). Regardless of the
time interval an alternative to using iptables is to use a dhcp
hostfile (passed to dnsmasq when invoked) and update that with 'MAC,
ignore' entries (and then sighup dnsmasq) as a means of filtering.
Add discovery-dhcp element to undercloud insallation
Merge pull request #19 from gfidente/dib_utils

Checkout dib-utils in addition to DIB from instack-virt-setup