Add licenses

[fernandezc]

Some files present in this repository are uploaded from external servers. Even if they are free to use, there are usually copyrights to include with the files.
I therefore propose to add a directory: Licenses and in this directory to place the license-xxx files where xxx is the name of the file or file directory.

@atravert can you check this because I don't know exactly where the files you added come from?

[atravert]

Yes, i'll do that.