temporary fix to gluster test. mkdirs fails if directory already exists; list after touch doesn't return
right file name. with these fixes, following gluster test passes.
mvn package -Dtest.profile=glusterfs -Dhadoop.version=2.3.0 -Dtachyon.underfs.glusterfs.mounts=/mnt/glusterfs/ -Dtachyon.underfs.glusterfs.volumes=testvol  -Dtachyon.underfs.glusterfs.mapred.system.dir=glusterfs:////mapred/system

Signed-off-by: rootfs <hchen@redhat.com>