Update Zeppelin shell scripts

I suggest Zeppelin use a consistent shell styleguide to make code easier to read\understand and less bug-prone.
For example, in travis CI server. once CI build finished, their VM instance terminates we have no chance to login and run any commands. That means unable to see why Zeppelin failed to start in CI server.

Also for normal uses, printing last few line after startup error (which normally includes stacktrace) is nice for user experience, too.