The API only consume and produce JSON format about proxi-schemas

[edeutsch]

Although I think the default should be JSON and most responses should be JSON, it seems reasonable that /datasets/{accession} could support XML as well since we already have an XML schema for that and some users may have a parser for it already. So I'm not sure that we should make this stark decision at this point.

[ypriverol]

We can leave this open for now @edeutsch . For the first implementation we go for json representation.

[ypriverol]

With the removal of the endpoint dataset/{identifier} #71 we should not allow for now XML.

[edeutsch]

I am conflicted on this.
In fact, I am starting to regret our decision to remove the /dataset/{identifier}
I am now not so certain that is a wise move. Maybe its behavior at the broker can be a bit different.