initial commit for MultiReQA 
looks like this dataset includes changes about many other files than the ones for multi_re_qa

Can you create another branch and another PR please ? > looks like this dataset includes changes about many other files than the ones for multi_re_qa
> 
> Can you create another branch and another PR please ?

Sure I will do that. Thank you.
Added MultiReQA, which is a dataset containing the sentence boundary annotation from eight publicly available QA datasets including SearchQA, TriviaQA, HotpotQA, NaturalQuestions, SQuAD, BioASQ, RelationExtraction, and TextbookQA. 