Reports/drop down filters

https://www.pivotaltracker.com/story/show/60725720

The filter panel should drop down vertically, rather than slide in from the left. The grid should move down to make space for the filter. (the tag area on the left of the image is not to be part of this story)

![image](https://f.cloud.github.com/assets/933400/1612948/f41864a4-55cd-11e3-80ae-2a1aa715136c.png)