Add StorageTier into Tachyon
fix some typo and format
small fix for getting block size
simplify code path of converting String to enum in StorageLevelAlias
modify according to latest code style
initial openstack integration

Signed-off-by: rootfs <hchen@redhat.com>
Merge pull request #520 from rootfs/wip-openstack

[Tachyon-191] deploy tachyon cluster on openstack
Merge pull request #467 from shimingfei/AddStorageTier

Add StorageTier into Tachyon[TACHYON-33 sub-task 4]