contacts and distributions as array?

The pattern of having contacts and distributions as key-value pairs is common in mcf. However this pattern is problematic in [mdme](https://github.com/osgeo/mdme). the `build form from json schema` is not able to manage this pattern in json-schema:

```
"contact": {
"title": "Contacts",
"patternProperties": {
"^.*": {
"type": "object",
```

I wonder if there are other scenario's with the same issue (there is for example the [PR with multiple contacts having the same role](#196) which is used as unique key).

I understand this is a massive breaking change, but just curious to hear your thoughts.