'response' item removed from default payload
In order to properly validate, the XML render now adds a 'response' root node to the default payload.
GET (resource): returned items are always wrapped in an 'items' list, regardless of the resource being accessed.
GET (item): 'item' key is used for the item, regardless of the resource being accessed.
Tests updated to reflect the changes to the response payload (no more 'response' key for JSON)
Changelog update with 'streamlined payload' (v0.0.3)
Merge branch 'streamlined-payload'