inspector: /json/version returns object, not array

Make /json/version return an object instead of an object wrapped in an
array.

Fixes: https://github.com/nodejs/node/issues/9760
PR-URL: https://github.com/nodejs/node/pull/9762


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Eugene Ostroukhov <eostroukhov@google.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>