Bug 1043496 - Default Image for Contacts When Image is Missing

I guess that you could write here "Build the template used for displaying the thumbnail image" and move "As long as all rows will have an image default or not, this is invoked at initialisation" to https://github.com/mozilla-b2g/gaia/pull/22160/files#diff-034ec030096933da02bf511b3f4a6133R187