Add editing of JSON within the Viewer

[njminchin]

Any chance of having the ability to edit JSON directly from the Viewer? It's hard seeing the objects that you want to remove in the Viewer and then feeling sad that you need to find these in the raw text and try to delete just those things without removing too many curly braces in the process :)

[SinghRajenM]

Please refer #201 (comment) and provide feedback if any.