support local async batching

[lucidd]

adding the batch parameter to async calls as its gonna be supported in salt with saltstack/salt#50546

[renner]

Looks good to me apart form the comments that I left.

[renner]

Okay, looks good to me now. This feature needs a minimum required Salt version though that is not even released yet, right? Is this patch backwards compatible in a way that the new batch parameters are ignored when working with an older Salt, or would you rather see this SaltInvocationError? I guess both should be acceptable.

[lucidd]

@renner so far it looks from @chiaradiamarcelo tests that it is backwards compatible since salt just ignores the additional parameters.

[chiaradiamarcelo]

@renner so far it looks from @chiaradiamarcelo tests that it is backwards compatible since salt just ignores the additional parameters.

yes, I can confirm that

[chiaradiamarcelo]

@lucidd shouldn't this PR include a class to map the 'batch started' salt event ?

[chiaradiamarcelo]

The following is an example of a 'batch-start' event json:

salt/batch/20190130132632115965/start	{
    "_stamp": "2019-01-30T12:26:32.178962", 
    "available_minions": [
        "mch-minion_1.tf.local"
    ], 
    "down_minions": [
        "mch-minion_2.tf.local"
    ],
    "metadata": {
        "suma-action-id": 3111,
        "suma-batch-mode": true
    }
}

[renner]

This patch looks still good to me. New unit tests might be a good idea though, or also a code example to understand how you would make use of the batching would be nice along with the other examples.