Handle recursive error details

[russcam]

An error in Elasticsearch can have multiple recursive details for the cause of the error e.g.

{
        "update": {
            "_index": "testindex",
            "_type": "docmodel",
            "_id": "xyz",
            "status": 400,
            "error": {
                "type": "illegal_argument_exception",
                "reason": "failed to execute script",
                "caused_by": {
                    "type": "script_exception",
                    "reason": "failed to run inline script [use(java.lang.Exception) {throw new Exception(\"Custermized Exception\")}] using lang [groovy]",
                    "caused_by": {
                        "type": "privileged_action_exception",
                        "reason": null,
                        "caused_by": {
                            "type": "exception",
                            "reason": "Custom Exception"
                        }
                    }
                }
            }
        }
}

Currently, the client parses only the top level type, reason and caused_by, but should handle nested caused_by objects

[gmarz]

This is now in 2.4.2, but leaving this open until it's ported to master. /cc @russcam

[russcam]

Thanks @gmarz, ported to master in cef52d8