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)

Instead of using a `for` loop, we should use underscore's `each` method like so:
```
_.each(scheduleItems, function(curScheduleItem) {
    var endMinute = curScheduleItem.endMinutes();
    // Rest of code here...
})
```

This is preferable because:
1. Our goal is to iterate through each element in the array and we don't really care about the index of the element. So there's no need to keep track of our own `idx`.
1. This creates a new scope for the loop body, which helps to prevent variable name collision (overwriting an old variable, or leaking a newly initialized one).