Adds a new BootInfo object with 2 fields:
* current_boot_mode - bios or uefi, detected from presence of /sys/firmware/efi
as per the following answer: http://askubuntu.com/a/162896
This field will be used for setting the boot_mode capability in ironic-inspector
* pxe_interface - PXE booting interface, if it can be detected.
This fields is already used by ironic-inspector, added here for consistency.
Change-Id: Ib36b592ffaba3bfa055d65c9526607867d302584
Partial-Bug: #1571580