ASM-2475 choose available raid controller

Previously RAID.Integrated.1-1 was always used, which might not
exist. This commit finds all RAID controllers, pick the first one and
defaults to integrated raid if none is found. Integrated raid is
preferred if both integrated and slot raid exist.
tweak bios_settings to work with strings

When running through puppet apply with a manifest generated by
yaml2manifest.rb, the bios settings come through as strings
rather than booleans.  This fixes up the munging to work with
string values of true and false
Merge pull request #74 from gavin-scott/asm-2475

ASM-2475 choose available raid controller