Securely allow multiple users to store their data

[KShivendu]

This needs:

• A proper authentication mechanism so that multiple users(trackers) can use a single DB server.
• We need to do some changes to the tracker so that the session tokens (or JWT) are stored securely and are used while making requests to the server.
• In the final stage, we would also like to encrypt all the data in the server so that even the server admin can't see the personal data of users.