add doc on glusterfs configuration
glusterfs configuration: fix reference link
in unit tests, if the temp environment folder already exists, remove it.
remove the testing folder after each unit test
integration test bug fix
revert MFT test as the previous version
Add TACHYON_MASTER_JAVA_OPTS for Master and TACHYON_WORKER_JAVA_OPTS for Worker to the default TACHYON_JAVA_OPTS.
fix a test bug
Update comment in the env template file.
further improve unit tests
Add JAVA_OPTS for Master and Worker for the GlusterFS.
Remove  from  definition in tachyon-glusterfs-env.sh.template because it will be added later.