Conform to the spec on individual resources

The way we represent a single “resource object” is by having it as a
object, and not as an array of length 1 with that single object in it.
This change is breaking and will bump the major version of this package.

Read more here:
http://jsonapi.org/format/#document-structure-individual-resource-repres
entations
A responder doesn't dumps it responds
Bump version