fixup wait_for_uaa bash

- quote vars to prevent globbing
- portable shebang
- strict mode bash

fixes #30

[#162468758]

jobs/credhub/templates/wait_for_uaa.erb

@@ -1,14 +1,16 @@
-#!/bin/bash
+#!/usr/bin/env bash
+
+set -euo pipefail
 
 <% if p("credhub.authentication.uaa.enabled") %>
   <% if p("credhub.authentication.uaa.wait_for_start") %>
 status=`curl --max-time 5 --connect-timeout 2 -k --silent <%= p(["credhub.authentication.uaa.internal_url", "credhub.authentication.uaa.url"]) %>/healthz`
-if [ $? -ne 0 ]; then
+if [ "$?" -ne 0 ]; then
   echo "Could not reach the UAA server"
   exit 1
 fi
 
-if [ $status != "ok" ]; then
+if [ "$status" != "ok" ]; then
   exit 1
 fi
 echo "Successfully connected to UAA, continuing startup"