Upload to azure blob store under {guid}/{provider}.
Update find so that provider and dataName are optional params i.e if you only pass a guid, startTimestamp, and endTimestamp, you will get all files for all providers and dataNames for the user within the provided timestamps.
Update how download gets the fileName for the download file. Since the files are nested now, [1] will point to a subfolder name.
Added express-validator to add configure validation logic for API payloads & params.