Add the PXE VendorPassthru interface to PXEDracDriver
Add the PXE VendorPassthru interface to PXEDracDriver

Without the PXE VendorPassthru interface to expose the "pass_deploy_info"
method in the vendor_passthru endpoint of the API the DRAC it can't
continue the deployment after the ramdisk is booted.

Closes-Bug: #1379705
Change-Id: I21042cbb95a486742abfcb430471d01cd73b3a4a

dims/ironic,SauloAislan/ironic,dims/ironic,hpproliant/ironic,ramineni/myironic,openstack/ironic,bacaldwell/ironic,NaohiroTamura/ironic,naototty/vagrant-lxc-ironic,redhat-openstack/ironic,supermari0/ironic,Tan0/ironic,NaohiroTamura/ironic,bacaldwell/ironic,naototty/vagrant-lxc-ironic,froyobin/ironic,naterh/ironic,devananda/ironic,pshchelo/ironic,Tehsmash/ironic,ionutbalutoiu/ironic,pshchelo/ironic,SauloAislan/ironic,rackerlabs/ironic,openstack/ironic,ionutbalutoiu/ironic,rdo-management/ironic