ZEPPELIN-5342: Fixes infinite loop in zeppelin.sh
ZEPPELIN-5342: Fixes infinite loop in zeppelin.sh

### What is this PR for?
If a user is passing an invalid argument to zeppelin.sh it freezes in an infinite loop. This small change changes this behavior and outputs usage information instead of looping forever in the `while` cycle.

### What type of PR is it?
Bug Fix

### Todos
* [ ] - Task

### What is the Jira issue?
https://issues.apache.org/jira/browse/ZEPPELIN-5342

### How should this be tested?

Just call `zeppelin.sh` with any type of unsupported arguments

Author: Pasha Finkelshteyn <pavel.finkelshtein@gmail.com>

Closes #4102 from asm0dey/patch-1 and squashes the following commits:

bd31fddf9 [Pasha Finkelshteyn] Fixes infinite loop in zeppelin.sh

apache/incubator-zeppelin,prabhjyotsingh/zeppelin,prabhjyotsingh/zeppelin,apache/zeppelin,apache/incubator-zeppelin,apache/zeppelin,apache/zeppelin,jongyoul/zeppelin,hammertank/zeppelin,jongyoul/zeppelin,fogbeam/zeppelin_mirror,jongyoul/incubator-zeppelin,zjffdu/zeppelin,prabhjyotsingh/zeppelin,apache/incubator-zeppelin,hammertank/zeppelin,hammertank/zeppelin,apache/zeppelin,jongyoul/incubator-zeppelin,hammertank/zeppelin,fogbeam/zeppelin_mirror,jongyoul/incubator-zeppelin,zjffdu/zeppelin,jongyoul/zeppelin,hammertank/zeppelin,prabhjyotsingh/zeppelin,prabhjyotsingh/zeppelin,zjffdu/zeppelin,jongyoul/incubator-zeppelin,jongyoul/zeppelin,apache/zeppelin,fogbeam/zeppelin_mirror,zjffdu/zeppelin,zjffdu/zeppelin,fogbeam/zeppelin_mirror,apache/incubator-zeppelin,hammertank/zeppelin,zjffdu/zeppelin,jongyoul/zeppelin,fogbeam/zeppelin_mirror,apache/zeppelin,apache/incubator-zeppelin,jongyoul/zeppelin,jongyoul/zeppelin,fogbeam/zeppelin_mirror,hammertank/zeppelin,apache/zeppelin,fogbeam/zeppelin_mirror,jongyoul/incubator-zeppelin,prabhjyotsingh/zeppelin,prabhjyotsingh/zeppelin,jongyoul/incubator-zeppelin,apache/incubator-zeppelin,zjffdu/zeppelin