zeppelin git commit: ZEPPELIN-2988. Zeppelin does not start new Livy session if yarn livy session application is killed

Repository: zeppelin Updated Branches: refs/heads/master 24f81426c -> d5a3c7444 ZEPPELIN-2988. Zeppelin does not start new Livy session if yarn livy session application is killed ### What is this PR for? This PR will display a warning message when the livy session is dead. It won't restart

zeppelin git commit: ZEPPELIN-2998. Fix bug in restarting interpreter in scoped mode

Repository: zeppelin Updated Branches: refs/heads/master 6b0f6e7a0 -> 24f81426c ZEPPELIN-2998. Fix bug in restarting interpreter in scoped mode ### What is this PR for? Fixed the bug mentioned in https://github.com/apache/zeppelin/pull/2554#discussion_r136703878 ### What type of PR is it?