Hours per week label

I added an "hours per week label" to the schedule page UI. I figured this would give students an easier and more accurate method of counting up their weekly hours rather than doing it manually. 

Here is a screenshot of the changes I made to the UI:
![newui](https://cloud.githubusercontent.com/assets/6456601/4179941/768239c4-36dd-11e4-9b65-c5f656a19971.png)

If I see "28 hours this week", I'm going to interpret that to mean 28*60 minutes of classes. I can understand that you want to include the 10-minute breaks between classes as part of class hours, but it's far simpler to count just in-class hours. What if there's a half-hour break between classes? Is that counted as part of class hours or not? What if we have classes that aren't exactly `30x - 10` or `30x` in length?

Counting hours should not be strictly tied to Waterloo's class lengths. The UI should do the least surprising thing.