TAJO-858 - Support for hadoop kerberos authentication in Tajo

Added new protocol message to exchange hdfs delegation token from TajoMaster to
client. This is needed when client needs to read from HDFS.
TAJO-858 - Support for hadoop kerberos authentication in Tajo

Added new class TajoConfException for execeptions caused
by wrong value in configuration.
Modified FileSystemUtil.getFileSystem code to wrap above
exception in IOException and rethrow it. This will help not
change any try/catch/throw code in client classes where
FileSystemUtil.getFileSystem is used.