add to first page of launcher a "news" line that link to Thymio website

[mbonani]

following Rss flux or a mechanism like for the firmware upgrader show when internet is present a news. The idea is to keep people up to date also in the launcher. The first new will be what https://www.thymio.org/fr/2019/05/03/thymio-suite/ and probably following will announce a new version of the software