Add support for sequence of transtypes

[kuhnuri]

Add support for sequence of transtypes

[jelovirt]

Thinking about this via the internal representation, the input job submission could be

{
  "input": "s3://example/b34a487a-b031-4bf0-893d-18bed8c4959b/src.zip!/start.ditamap",
  "output": "s3://example/b34a487a-b031-4bf0-893d-18bed8c4959b/res.zip",
  "conversions": [
    {
      "transtype": "graphics",
      "params": {},
      "priority": 0
    },
    {
      "transtype": "ooxml",
      "params": {},
      "priority": 0
    }
  ]
}

Then the conversion is in progress, the job state could be something like

{
  "input": "s3://example/b34a487a-b031-4bf0-893d-18bed8c4959b/src.zip!/start.ditamap",
  "output": "s3://example/b34a487a-b031-4bf0-893d-18bed8c4959b/res.zip",
  "id": "cd010166-7b69-4c9a-a3d2-697a7b6ac280",
  "created": "2018-03-23T08:58:35.208Z",
  "conversions": [
    // This is an active conversion
    {
      "id": "cd010166-7b69-4c9a-a3d2-697a7b6ac280_1",
      "input": "s3://example/b34a487a-b031-4bf0-893d-18bed8c4959b/src.zip!/start.ditamap",
      // The job originally got the output above, but replaced it with this temporary storage
      "output": "s3://example/b34a487a-b031-4bf0-893d-18bed8c4959b/tmp.zip!/start.ditamap",
      "transtype": "graphics",
      "params": {},
      "status": "process",
      "priority": 0,
      "start": "2018-03-23T08:58:35.208Z",
      "finish": null,
      "worker": "worker"
    },
    // This conversion is still in the queue
    {
      "id": "cd010166-7b69-4c9a-a3d2-697a7b6ac280_2",
      // This will be populated from previous conversion's output
      "input": null,
      // This will be populated from root output
      "output": null,
      "transtype": "ooxml",
      "params": {},
      "status": "queue",
      "priority": 0,
      "start": null,
      "finish": null,
      "worker": null
    }
  ]
}

[jelovirt]

Implemented.