MegaRAID Plugin: Add support of Disk.STATUS_FREE
MegaRAID Plugin: Add support of Disk.STATUS_FREE

 * Treat 'UGood' and 'UBad' as free disk.

 * Update algorithm of disk status query to support show spare disk with
   sector error as SPARE|ERROR

Changes in V2:

 * Fix the incorrect data assign:
    disk_status == Disk.STATUS_UNKNOWN
   Should be:
    disk_status = Disk.STATUS_UNKNOWN

Signed-off-by: Gris Ge <e24f3acbe39bf94f92e8af3c48f8852106ad5ad7@redhat.com>

jumitche/libstoragemgmt,joehandzik/libstoragemgmt,jumitche/libstoragemgmt,tasleson/libstoragemgmt,lazy404/libstoragemgmt,cathay4t/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,libstorage/libstoragemgmt,lazy404/libstoragemgmt,tasleson/libstoragemgmt,cathay4t/libstoragemgmt,libstorage/libstoragemgmt,cathay4t/libstoragemgmt,libstorage/libstoragemgmt,tasleson/libstoragemgmt,tasleson/libstoragemgmt,lazy404/libstoragemgmt,lazy404/libstoragemgmt,joehandzik/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,jumitche/libstoragemgmt,joehandzik/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,jumitche/libstoragemgmt,cathay4t/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,joehandzik/libstoragemgmt,libstorage/libstoragemgmt,jumitche/libstoragemgmt,tasleson/libstoragemgmt,libstorage/libstoragemgmt,cathay4t/libstoragemgmt