Merge pull request #18 from calvinjia/master

Logging changes
format code
add more unit tests. format code.
add more unit tests.
remove redundant code.
remove TestReadBig.java
rename TFileXStream to be FileXStream.
update TachyonFile, OsStream, InStream API and corresponding Tests.
let liststatus of hadoop fs implementation handle dir.
better logging in Hadoop FS impl
better logging.
more unit tests, with focus on TachyonFileTest.
WorkerServiceHandler and MasterInfo tests