Fixes 944 | Remove the check for returning more than one JSON result in Response Plugin

[bbbco]

Fixes https://github.com/Kong/insomnia/issues/944

Removes the check for returning more than one JSON result in the Response Plugin. If the result is an array of objects, the code following the removed check will just stringify the result. This allows the response to be more easily chained and parsed by the JSONPath plugin.