Make ufscluster singleton for the entire jvm process
Enable integration test for LocalTachyonClusterMultiMaster
Disable the client instance cache in hdfs to avoid certain FileSystem closed exception issue.
Make disable.cache=true only work for test.
Disable the hdfs client instance cache for JournalTest
Merge pull request #133 from GraceH/integrationPerf

Make ufscluster singleton for the entire jvm process