TACHYON-198 Remove Reference to UserConf from the code.
TACHYON-198 Next stop, remove UserConf class.
TACHYON-198 Fix TestDFSIO to pass TachyonConf to TFS.
TACHYON-198 Address comments from pull requests.
Add helper method to return default user write type from TachyonConf.
Add JavaDoc to helper methods in TachyonConf to store and load from Hadoop Configuration.
Move the mkdir in multi master after the set other properties.