Start the MDS calendar weeks on Mondays

[joelostblom]

I'll admit this is mostly because I get myself confused when I look at the MDS calendar and if you think students will be confused if we switch, then let's keep it as is. In an attempt to argue my personal preference with from a more objective angle, Mon is ISO 8601, which is what we promote for date formats otherwise (but I agree is not as important here).

[ttimbers]

In North America, most calendars typically begin on Sunday and end on Saturday. Since we are in NA, I suggest we stick with this. We discussed this briefly in DSCI 523 when learning {lubridate} in R (it takes a NA stance naming Sunday as day 1 of the week). I am happy to be outvoted if others prefer this though.