Convert (Elsevier) ScienceQA data

[riedelcastro]

As part of #2. Maybe something like

"question": "dataset_for(parsing, ?)",
"support": [ "list of paragraphs created by a heuristic" ]
"answer": ["list of answers from wikipedia"]

We should also generate cloze questions from paragraphs that mention the same entity

"question": "we used the ? corpus for our parsing model",
"support": [ "list of paragraphs created by a heuristic involving parsing, but removing the sentence that is the basis for the cloze question" ]
"answer": ["answer as taken from the cloze question sentence"]

We can also create cloze questions from the highlights.