Ironic: Add deploy kernel and deploy ramdisk to driver_info

Pass deploy kernel and deploy ramdisk as parameters to the driver
to enable Ironic to support different deploy provisioning
methods using the same flavor. This patch is part of the
https://blueprints.launchpad.net/ironic/+spec/add-node-instance-info
work which is separating the instance-level data from the driver-leval
data in the Node's resource of Ironic, once it's finished another patch
will be submitted to DevStack to remove the part of the code which is
adding the deploy kernel and deploy ramdisk parameters to the flavor,
for now a TODO was left inline as a reminder.

Change-Id: Id7cfb17cc6f6133964be139bfedbca1dc644b9cd
Implements: blueprint add-node-instance-info
Merge "Ironic: Add deploy kernel and deploy ramdisk to driver_info"