DAM > Add an extension tag in the results listing

• Tag “Extension” under the thumbnail (get the extension from the main blob filename, not the title as it may be different)
  Do not display the extension, if any, of the document title in the box layout.

Add a tag with the lower case extension inside bellow the thumbnail: different colors for audio / video / images / other
[with a color different for each type?=> 1d (nice to have]