Implement skeleton of what a BIOS Driver and Setting must provide.

This has just enough functionality to get and set BIOS settings from the
rails console on Dell Poweredge R-series gear.  It is not exposed to the
core bayond that.
Merge pull request #18 from VictorLowther/implement-basic-bios-support-on-poweredge-r-gear

Implement skeleton of what a BIOS Driver and Setting must provide.