Show all custom properties on image detail page

Display all custom properties of a given image on the Image Detail
page. Titles for the custom properties can optionally be displayed
if they are defined in IMAGE_CUSTOM_PROPERTY_TITLES in local
settings.

Change-Id: I7366ec06bf7d77810d7d8fd343390bc1a5eb0674
Closes-Bug: #1249543
Merge "Show all custom properties on image detail page"