: Improve status (attribute) reporting of RAID LVs via 'lvs'

I have a set of three patches that should improve the accuracy of the 'attr' field of 'lvs' when reporting on RAID logical volumes.

1) New lv_raid_dev_health() function:
Provides a clean interface for RAID to get kernel status
2) Cached lv_raid_dev_health results:
A suggested optimization, but isn't necessary.
3) Improved attribute reporting of RAID LVs via 'lvs' Fixes bz903249 and other complaints

brassow