Testing the names of all weekdays in the month, agendaView and weekView views

For the `month`, `agendaView` and `weekView` views I'm just looking at the first (and most likely only) element that fits the `.fc-view thead .fc-DAY` selector. From that point onwards I check the contents of every weekday header because the tests are similar for all views I've taken the liberty to throw them in a `forEach` loop. Not sure if it is acceptable, but it makes for less SLOC.