Support JSON metadata

This allows JSON metadata to be supported, in addition to CSV metadata.

JSON metadata follows a similar format. It should contain an array of objects, one object per file to represent. Its keys should contain data in the same format that the CSV columns would contain. Rather than have separate JSON metadata code in archivematicaCreateMETS2, this just adds a new microservice to translate JSON into CSV at the end of ingest.

Supported JSON resembles this:

```json
[
	{
		"filename": "foo.txt",
		"dc.title": "Some text file",
		"dc.author": "Me"
	}
]
```

In addition, this branch also adds supported for qualified Dublin Core. A couple of cleanups in these areas of code snuck in too.

This needs to be squashed when it's merged.