Improve readability of multi-day events

Multiday events appear essentially as black text on a black background.

![image](https://cloud.githubusercontent.com/assets/357481/4477116/76fd9294-497b-11e4-9f89-8a3783af75dc.png)

This changes the text color for multiday events to nearly white on the same black background. Hover color is not changed.

![image](https://cloud.githubusercontent.com/assets/357481/4477129/9b9f9b38-497b-11e4-8044-a013f7349c1f.png)