Add copyright headers

Dear @anacosta ,

We analysed the current code and found that copyright headers were missing in all the files. We have produced a Merge Request to show mainly the type of headers we expect when IP Reviewing open source code.

We invite you to check each change because there are some cases in which the addition of the header can create issues, like in files which are input for another process and we are not sure if comments or a header are expected. Please have a look at them.

You'll notice we've assigned ownership to "LOBA", as indicated by email.

You will notice as well that in each file there is a placeholder for the Contributors (last section in the header). Feel free to add your name and contribution, or other's names there. As an example: Tasos Nikolakopoulos - Author, John Smith - Coauthor, etc.

Feel free to be inspired and/or accept the whole Merge Request.

Thanks a lot

/cc @asgomes @hugopeixoto