Date format search develop

Fix the formatting of the date in the central panel. The date was off by 12 hours due to the fact that am or pm was not indicated.
Also handled the fact that the acquisition could be null. This is mainly relevant for develop. see gh-1240

To test:
 * Log in as user dv password ome
 * search for images e.g. IAGFP in insight, and perform the same search in web
 * Check that the time in the central panel is the same.

This PR does not address the general date formatting issue reported on the trello card https://trello.com/c/2vdtlj9e/267-date-format-and-display

I have attached screenshot of the date formatting before and after the change. 
cc @mtbc @dominikl 

Before:

![datebeforechange](https://cloud.githubusercontent.com/assets/1022396/3747888/4d0d7806-17d4-11e4-80f9-e95757699175.png)

After

![dateafterchange](https://cloud.githubusercontent.com/assets/1022396/3747889/58742b40-17d4-11e4-844d-a9ef8899e41c.png)