Always apply border radius to start and end date

The rounded corners on start and end date isn't applied correctly on days at the start of the week.

Before patch:

![before](https://cloud.githubusercontent.com/assets/2064938/4025054/9f970800-2be6-11e4-9aea-d5c62d75e0fa.png)

After patch:

![after](https://cloud.githubusercontent.com/assets/2064938/4025055/aaa9bf4e-2be6-11e4-95f4-87b6c2d388b5.png)