Add functionality for add operation

[mayankshah1607]

The scope of this issue is simple - complete the logic for performing add operation on calling a POST request at /math/add.
Add relevant tests under tests/test.js

[abhagsain]

I'm on it. Do we have to create UI also? or any HTTP client is fine?
Postman etc?

[mayankshah1607]

Creating a client is not required. :)

[phernandoe]

Whoops I totally forgot to comment. I've also taken this issue if you don't mind

[mayankshah1607]

Hi! I have opened a new issue for more people to work on. Feel free to check it out - #9