Weekly metrics

(Fulfills #70, per @redsquirrel)

A basic dashboard that shows the count of appointments for the current week:

![](https://photos-5.dropbox.com/t/0/AAClq81XqRKGvbbcI7JSKrRdQOqR9d06K2QZPVUy9KVgNw/12/12686470/png/1024x768/3/1393290000/0/2/Screenshot%202014-02-24%2015.58.04.png/8XLM-bsQbEzzojdEDtL5vy3t-TmihSnhG967Dc7VNIM)

...and has a way to show appointments for a previous week:
![](https://photos-3.dropbox.com/t/0/AACQUWOOB-JaynLerA_QVem5BLRTJgjinEF0LwWXxG6KcQ/12/12686470/png/1024x768/3/1393290000/0/2/Screenshot%202014-02-24%2015.58.28.png/zBiAQZ-7nXDcEWgrl090YXYzTKsyVNBAlDJU3LVDf94)