Remove the RIS and RTF export types for a publication.

#5957 

Output:
![selection_110](https://cloud.githubusercontent.com/assets/4497748/2811058/730672f0-ce01-11e3-81e6-c315ebb0a934.png)
![selection_111](https://cloud.githubusercontent.com/assets/4497748/2811059/7322af1a-ce01-11e3-9b7d-77733892aa04.png)