(FACT-652) Cherry-pick lost blockdevice UUID fact back into master

This commit cherry-picks the blockdevice UUID fact back into master,
which was lost during the facter-2 / master merge.

Original commit (f7b09c73):
(FACT-234) Add blockdevice uuid fact

Add facts to show the uuid of partitions.

Looks for the partition of block devices found in /sys/block/<device>/<device>*
Then looks for the a link to the partition device in /dev/disk/by-uuid.  The link name is the UUID.

JIRA: FACT-234
(FACT-652) Schema update for blockdevice UUID cherry-pick

Original commit (cf76c4aa8):
(fact-234) Add newly defined blockdevice dynamic facts to the schema