better coloring for blackout days

![2014-06-15_14h35_53](https://cloud.githubusercontent.com/assets/658431/3278462/0dc08b48-f3c1-11e3-9656-638227cde657.png)
![2014-06-15_14h36_08](https://cloud.githubusercontent.com/assets/658431/3278463/0f66eb0e-f3c1-11e3-9a58-b5195cb1381b.png)

Closes #1133 Problem with the Calendar control