Add csqa and siqa

[yulinggu-cs]

Added commonsense_qa and social_iqa as downstream evaluation task.

Example instance from commonsense_qa:

{'id': 'e68fb2448fd74e402aae9982aa76e527',
    'question': 'Where are  you likely to find a hamburger?',
    'question_concept': 'hamburger',
    'choices': {'label': ['A', 'B', 'C', 'D', 'E'],
    'text': ['fast food restaurant', 'pizza', 'ground up dead cows', 'mouth', 'cow carcus']},
    'answerKey': 'A'}

Example instance from social_iqa:

{'context': 'Jordan was in charge of taking the food on the camping trip and left all the food at home.',
     'question': 'How would Jordan feel afterwards?',
     'answerA': 'horrible that he let his friends down on the camping trip',
     'answerB': "happy that he doesn't need to do the cooking on the trip",
     'answerC': 'very proud and accomplished about the camping trip', 'label': '1'}

To include in a training config, use:

  - label: commonsense_qa
    type: downstream
  - label: social_iqa
    type: downstream

[epwalsh]

Thanks @yulinggu-cs! My only comment is about the CHANGELOG

[epwalsh]

This should go up under the unreleased section

[yulinggu-cs]

Thanks! Moved that just now!