GIRAPH-514: DiskBackedMessageStores should take advantage of machines with multiple disks
GIRAPH-514: comment fixup
Merge branch 'trunk' of https://git-wip-us.apache.org/repos/asf/giraph into trunk
GIRAPH 514
GIRAPH 514
Merge branch 'trunk' of https://git-wip-us.apache.org/repos/asf/giraph into trunk