Add Italian translation

[santisoler]

After @Magicianred comment on #12 would be great to have an Italian translation of the README.md and for the license texts.

The changes that would be needed are:

• Add a new it folder containing a README.md file which should be a translation from the English README.md.
• Add the Italian version of the license texts.
• Add a badge on the main README.md pointing to the Italian translation folder.
• Add a badge on it/README.md pointing to the main README.md (see the other translations).

You don't need to translate the licenses texts, they can be downloaded from Creative Commons website. The last time I checked, only the English version of the license texts could be downloaded as a .txt file, so we used to have to reformat the HTML files as .txt files. After creativecommons/cc-legal-tools-app#56 has been merged, we should be able to download the txt files from CC, but I don't know if that code has been deployed yet. I'll ask and comment here if I hear some news.

[Magicianred]

Great :)