BIR-4: Fetch user metadata for the set of given set of SO users

[devjyotipatra]

Along with fetching the user metadata from SO apis, we need to convert the user_reputation on some date (rep_created_date) to some previous date (question_created_date)

[arvindpdmn]

Some thoughts:

• If a low reputation user asks/answers a question, the question is probably beginner level
• If a high reputation user asks a question, the question is probably advanced level
• Can't conclude much if high reputation user answers a question?