Add json format for test results + other enhancements

[johnsusek]

This adds support for structured JSON test results that was just added to the master branch of elastalert.

Please see Yelp/elastalert#1897

When using the new option format=json, test results will look like this:

{
  "hits": 11,
  "terms": {
    "syslog_severity_code": 6,
    "service": "Vpxa",
    "tags": [],
    "syslog_severity": "informational",
    "@timestamp": "2018-09-10T18:16:23.461Z",
    "syslog_facility": "user-level",
    "host": "c5014-cesx121.ms",
    "@version": "1",
    "dept_id": "ms",
    "message": "- - [Originator@68762018-09-10T18:16:23.450Z Vpxa: verbose vpxa[FFC9AAE0] [Originator@6876[VpxaHalCnxHostagent::ProcessUpdate] Applying updates from 11843011 to 11843012 (at 11843011)",
    "syslog_pri": "14",
    "type": "syslog",
    "syslog_facility_code": 1
  },
  "name": "test321",
  "success": true,
  "days": 1
}

[martijnrondeel]

Thank you for the PR! Is it ready to be merged or still WIP?

[johnsusek]

Yes, it is ready to go!

[johnsusek]

I've closed the other duplicate PRs. This is ready to be merged. Thank you :)

[johnsusek]

@martijnrondeel Hi, any chance you could merge this when you have a moment? We are looking to release a test of our UI internally, that uses these changes. Yelp has already merged the needed changes into their latest code.

Here is a preview of the UI:

https://github.com/ServerCentral/praeco

Thank you :)

[martijnrondeel]

Thanks for your work! Going to merge this now and release a new version.

[martijnrondeel]

It's available now in the latest release (0.0.13).