Apply transaction management on placing order

[anantjain6]

In current scenario when order gets placed then the ordered quantity of product gets deducted to the the available quantity of products
Using transaction management make sure that placing order and deducting product quantity executed in transaction

[sandeshdahake]

Please review and let me know if you need more modifications.

I will strongly suggest use of Lombok to reduce boilerplate code in the project. Also I have few more ideas which will help in maintainability.