Add a license to the code

[gitansh95]

Short Description

Choose from one of the open source licenses for our project.

Need

The license will allow the code to be shared, distributed and modified under defined terms and conditions.

Possible Implementation

We can place the license text in a file named LICENSE.txt (or LICENSE.md) in the root of the repository.
We may also include information about the license in our README.
All code files must have a header with the license including authors' and organization's names where the software was originally developed.

[mchandra]

use GPL v3