Added poster to DisplayShow page.

Added a poster to the show header on the show display page. 

Before:
![sb-before](https://cloud.githubusercontent.com/assets/1240778/4512083/44c966dc-4b3c-11e4-84cc-5551809c6561.png)
After:
![sb-after](https://cloud.githubusercontent.com/assets/1240778/4512084/477858c0-4b3c-11e4-8446-8f5cbc868c92.png)