Change the "date" markup for a recurring event.

#6412 

This PR changes the text layout for recurring events.
Before:
![selection_405](https://cloud.githubusercontent.com/assets/4497748/3672370/b50d3bce-125e-11e4-8da7-bf79cacd6396.png)

After:
![selection_406](https://cloud.githubusercontent.com/assets/4497748/3672374/bafda8a2-125e-11e4-8593-8daff01aa7f2.png)


My first thought was that it was better to override the theme function.  Then I looked at the theme function date_display_combination.