Add Location header to job run creation

[nkijak]

To use the job run API you must first create a run to generate the ID to use. This ID is included in the returned content, but it would be helpful to include a Location header with the full URL to the run resource given that the runs API is quite different from the creation or other APIs.

Currently

$ http -v localhost:5000/api/v1/namespaces/dataeng/jobs/edw-pull/runs < fake_run.json
POST /api/v1/namespaces/dataeng/jobs/edw-pull/runs HTTP/1.1
Accept: application/json, */*
Accept-Encoding: gzip, deflate
Connection: keep-alive
Content-Length: 109
Content-Type: application/json
Host: localhost:5000
User-Agent: HTTPie/1.0.3

{
    "runArgs": {
        "end": "2020-01-02T00:00:00",
        "env": "dev",
        "start": "2020-01-02T00:00:00"
    }
}

HTTP/1.1 201 Created
Content-Length: 271
Content-Type: application/json
Date: Sat, 11 Jan 2020 19:34:52 GMT

{
    "createdAt": "2020-01-11T19:34:52.432Z",
    "nominalEndTime": null,
    "nominalStartTime": null,
    "runArgs": {
        "end": "2020-01-02T00:00:00",
        "env": "dev",
        "start": "2020-01-02T00:00:00"
    },
    "runId": "261202b3-8fd7-42dc-8446-9575f39e2dc1",
    "runState": "NEW",
    "updatedAt": "2020-01-11T19:34:52.437Z"
}

Requested response
Note Location header

HTTP/1.1 201 Created
Content-Length: 271
Content-Type: application/json
Location: localhost:5000/api/v1/jobs/runs/261202b3-8fd7-42dc-8446-9575f39e2dc1
Date: Sat, 11 Jan 2020 19:34:52 GMT

{
    "createdAt": "2020-01-11T19:34:52.432Z",
    "nominalEndTime": null,
    "nominalStartTime": null,
    "runArgs": {
        "end": "2020-01-02T00:00:00",
        "env": "dev",
        "start": "2020-01-02T00:00:00"
    },
    "runId": "261202b3-8fd7-42dc-8446-9575f39e2dc1",
    "runState": "NEW",
    "updatedAt": "2020-01-11T19:34:52.437Z"
}

[wslulciuc]

@nkijak Agreed! Would you like to add this feature? Here's a link to a great example on how we might initialize the Location header returned by JobResource.createRun(): Example ex10_2: Link Headers

[nkijak]

@wslulciuc Yep. Happy to take this one on.

[wslulciuc]

@nkijak Thanks! For pointers on how to get started, checkout CONTRIBUTING.md.

[wslulciuc]

Fixed #701. Thanks @nkijak for your contribution!