Add LICENSE file

[valenting]

A license needs to be chosen for this repo.
All contributors need to agree with the chosen license.
A list of contributors is enclosed below:

• Dan Serban @dserban
• Razvan G @UberNuke

(This message was generated automatically.)

This project is not essential for the ROSEdu organization and can be removed.

[tudalex]

Do you want ownership of this repo? Since you the major contributor to it.

I forked it under my own account, it can be removed from the ROSEdu organization.

[mihaimaruseac]

The projects are kept into the ROSEdu organization GitHub for bragging purposes.