PR #4 fixed a scaling issue by removing progressive downscaling.

This ensures that the returned values are correct but takes slightly longer to calculate. If the calling system is aware of what the sizes should be, then they may be willing to accept a slight margin for error in the returned values. Have a flag to allown progressive downcaling to be enabled/disabled depending on needs of consuming app.

Either on startup or per request? Or a default of 'correct', but can be overriden per request.

After processing an image, remove any working artifacts (e.g. .tiff file)

If I make a call to POST /convert with an empty ({}), or unrecognised body I get a 200 response code back, with the following JSON:

{
    "message": "Unknown operation",
    "status": "error"
}

This should be a non 2xx (400?) response.

Allow more operations to be specified? Currently you can:

• "ingest" - create JPEG2000 from source and then generate thumbnails
• "derivatives-only" - generate thumbnails from existing JPEG2000.

Other options could be:

• "thumbnails" - create thumbnails only, from a non-JPEG2000 only
• "convert" - create JPEG2000 from source without generating thumbnails

Both of these options can be achieved by calling "ingest" and disregarding some of the output but that incurs unnecessary compute cost.

2 dependencies within the project are not pinned correctly and cause the build to fail.

These are werkzeug in flask and PyYaml in awscli. based on this stack overflow it looks like pinning pyyaml may have security implications