This element installs oat-client on the image, that's necessary for
trusted boot feature in Ironic to work. This element only works on Fedora.
Intel TXT will measure BIOS, Option Rom and Kernel/Ramdisk during trusted
boot, the oat-client will securely fetch the hash values from TPM.
Change-Id: I0f1221b5708e9a5792df62ee6e73034f8bf1577c
