[Tachyon-26] test UnderFileSystem.get() code path in Glusterfs Cluster.
Fix the dependency issue in gluster test profile;
Update gluster test instruction in glusterfs setup document.

Signed-off-by: rootfs <hchen@redhat.com>
use glusterfs scheme for under fs address

Signed-off-by: rootfs <hchen@redhat.com>
fixes issues found in glusterfs test
on glusterfs, mkdirs on existing dir returns false. So a new unit test should delete the directory before mkdirs.
Not use glusterfs root path for unit test, change getUnderFilesystemAddress() to use sub dir.

Signed-off-by: rootfs <hchen@redhat.com>
Merge pull request #321 from rootfs/tachyon-26

[Tachyon-26] test UnderFileSystem.get() code path in Glusterfs Cluster.
format the code; add worker client retry logic