new chart for rdvs by statuses on public stats pages
Created by: adipasquale
https://trello.com/c/EXxWdesz/1052-ajouter-un-graphique-sur-la-page-stats-avec-les-statuts-des-rdvs
Screenshot (with prod dump)
slightly tricky because we're using chartkick + chart.js which doesn't let us use stacked: :relative option cf doc, so I used some ruby ninja-fu but it's not incredibly readable
thanks for the very precise specs @guillett waiting rdvs because I think it only makes it harder to read without giving any additional infos as it's a very transient state so they'll ever be a maximum of a few rdvs in that state at a time