update main.py

[anushka17agarwal]

update main.py

[mihirs16]

1. Don't have to use anything from keys_init.py
2. Use the Debug/Message objects from utils.py to print messages to screen.
3. For Encrypt and Decrypt, you don't have to use generate_encryption. Instead you have to use encryption from encryption.py
4. In Add, Subtract and Modify you need to check if the file is encrypted or not. If file is encrypted, then you must decrypt it, call the add function (or for now, just a message would do) and then re-encrypt it. If not encrypted, you can directly call the add function (for now message would do).