Add feature to read CSV files

[oyekanmiayo]

Right now, the application reads purely from JSON, but most of the documents coming in are in .xls format (which can be exported easily to .csv). So, the goal here is to add a feature that will allow this script to read files in CSV format.

A few pointers:

• Maintain "configurability". Make it possible for users to decide if they want to read just JSON files, just CSV files, or both.