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)

Please wrap the long line like this:

```js
this.schedule.on('change:start_date change:end_date change:total_hours',
        this.render, this);
```