DRAC vendor passthru for BIOS settings management

Among other things we want to do with Dell Poweredge gear, we need to be able to manipulate the BIOS settings of the servers to tune them in accordance with what their workload is. This spec will expose the vendor passthru methods needed to let external services get, set, and commit changes to the BIOS settings. This spec will assume that the external service knows exactly what it is doing with the specific hardware it will manage, and it will not attempt to standardize, normalize, or simplify the exposed settings in any way beyond some minimal convienence measures and what is needed to map between XML and JSON.