Converting HTML entities in ImageGalleryViewController

Using GTMNSString+HTML.m from Google Toobox for mac, converting html entities for better display in ImageGalleryViewController

Example
For the title of an image asset in an Image Stop,
"Intérieur de l&#039;église" becomes now "Intérieur de l'église" : far more easier to read :-)

Before
![capture decran 2013-05-25 a 17 20 18](https://f.cloud.github.com/assets/314697/564266/d46842a0-c54f-11e2-9fc5-d4cb626ae59c.png)

After
![capture decran 2013-05-25 a 17 23 12](https://f.cloud.github.com/assets/314697/564268/dcdb3cb2-c54f-11e2-9e00-79fe894a382a.png)