Zeppelin：和hive相关的一个bug，以及解决方案

java.lang.NullPointerException	at org.apache.zeppelin.hive.HiveInterpreter.getConnection(HiveInterpreter.java:184)	at org.apache.zeppelin.hive.HiveInterpreter.getStatement(HiveInterpreter.java:204)	at org.apache.zeppelin.hive.HiveInterpreter.executeSql(HiveInterpreter.java:233)	at org.apache.zeppelin.hive.HiveInterpreter.interpret(HiveInterpreter.java:328)	at org.apache.zeppelin.interpreter.ClassloaderInterpreter.interpret(ClassloaderInterpreter.java:57)	at org.apache.zeppelin.interpreter.LazyOpenInterpreter.interpret(LazyOpenInterpreter.java:93)	at org.apache.zeppelin.interpreter.remote.RemoteInterpreterServer$InterpretJob.jobRun(RemoteInterpreterServer.java:300)	at org.apache.zeppelin.scheduler.Job.run(Job.java:169)	at org.apache.zeppelin.scheduler.ParallelScheduler$JobRunner.run(ParallelScheduler.java:157)	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)	at java.util.concurrent.FutureTask.run(FutureTask.java:262)	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:178)	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:292)	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)	at java.lang.Thread.run(Thread.java:744)