Structured output needs to handle nil value cases

[mikewiebe]

Summary:
The behavior has changed in h_dev images for some fields that have structured output.

For example:

On h_dev:

{
  "ins_api": {
    "type": "cli_show",
    "version": "1.0",
    "sid": "eoc",
    "outputs": {
      "output": {
        "input": "show snmp",
        "msg": "Success",
        "code": "200",
        "body": {
          "sys_contact": null, <----------- Display unset values as null, (translates to nil in ruby)
          "sys_location": null,

On Older Images:

{
  "ins_api": {
    "type": "cli_show",
    "version": "1.0",
    "sid": "eoc",
    "outputs": {
      "output": {
        "input": "show snmp",
        "msg": "Success",
        "code": "200",
        "body": {
          "sys_contact": "",  <----------- Display unset values as empty
          "sys_location": "",

This update fixes our infra to handle both cases.