Trying to fix HBase support issue in TACHYON-27
Optimize imports; reformat code style; improve javadoc; remove the commented code.
Linked to TACHYON-46 in Javadoc
Improve Javadoc comments
Merge branch 'master' of https://github.com/amplab/tachyon into createNonRecursive
createNonRecursive() should throw exception if parent directory doesn't already exist,  which is extremely important for HBase to do fencing of dead region servers properly.
Fix the bug mentioned in [TACHYON-66]

Fix the bug mentioned in [TACHYON-66] "The memory usage statistics is
not right when multi-user cache the same file and stops their
connection".
Change the synchronized range
new example
Synchronize on final objects
Style
Update comments
Merge pull request #362 from calvinjia/tachyon-40

[TACHYON-40] Synchronize on final objects
[TACHYON-68] When file is completed, reject all write requests on client
side
removed constants and moved to test
Merge pull request #363 from dcapwell/TACHYON-68/reject-client-update

[TACHYON-68] When file is completed, reject all write requests on client
return immutable copy of children to avoid concurrent read and write
format
Merge pull request #355 from dcapwell/example-nobuffer

new example
Merge pull request #322 from pfxuan/createNonRecursive

Trying to fix HBase support issue in TACHYON-27