Support passing XML as the BODY as well

[ebebbington]

Running into cases where because the XML i'm trying to parse is so large, passing it as a query string results in a an error: URI too long

You can use this as an example input: https://boardgamegeek.com/xmlapi2/thing?id=13&versions=1&stats=1

It'd be great if your API could also support a POST method to pass the data in as the body?