Support serialise nested object as nil

[ignacio-chiazzo]

We have to support sending a nested object as nil so as to delete the object.

  objectUpdate(input: $input) {
        userErrors { field, message }
        object {
          id
          title
          suboject {
            id
            name
          }
        }
      }
    }

To do that we have to modify the serialise function.

[see-mack]

This is also affecting the android client. Is there an open issue to fix that as well?

[ignacio-chiazzo]

I created this ticket but haven't had a chance to look into it. It's not on my TODO plan now, but I can take a peek after.

[ignacio-chiazzo]

Closing in favour of #8