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.
Merge pull request #322 from pfxuan/createNonRecursive

Trying to fix HBase support issue in TACHYON-27