Climate activist Greta Thunberg has joined French agitators, lending her "How dare you?" indignation to demonstrations that began over education grievances but soon devolved into violent, migrant-driven riots.In a video posted to her Instagram, Thunberg encouraged agitators to attend what became a clash between rioters, law enforcement and local business owners – calling on her followers to support the cause."French students are out continuously facing extreme police brutality just for asking for their basic rights. And now it’s time for us to step up because they cannot carry this alone," Thu...