Update JSON to SQuAD2.0

[fmikaelian]

• Add question id on addAnnotation() method
• If answer is empty on addAnnotation() add "is_impossible":true otherwise false

{
    "version":"v2.0",
    "data":[
       {
          "title":"Beyonc\u00e9",
          "paragraphs":[
             {
                "qas":[
                   {
                      "question":"When did Beyonce start becoming popular?",
                      "id":"56be85543aeaaa14008c9063",
                      "answers":[
                         {
                            "text":"in the late 1990s",
                            "answer_start":269
                         }
                      ],
                      "is_impossible":false
                   },
                   {
                      "question":"What areas did Beyonce compete in when she was growing up?",
                      "id":"56be85543aeaaa14008c9065",
                      "answers":[
                         {
                            "text":"singing and dancing",
                            "answer_start":207
                         }
                      ],
                      "is_impossible":false
                   },

[fmikaelian]

This may help for id https://github.com/kelektiv/node-uuid #29

[rsjain1978]

@fmikaelian I have been able to migrate the application to support SQuAD2.0 format including the above-requested enhancement.

[fmikaelian]

Hi @rsjain1978 Thank you for sharing!

We would be very happy to support both SQuAD 1.1 and SQuAD 2.0 in the annotator. We just need to find a proper way to handle this feature from the user point of view.
Could you describe your solution? Or open a PR with what you have so we can review together?