Fix crash when looking at images in campaign view

Change-Id: I9254277065a89effa7c9835cc20451043561d16b

Author: yuvipanda

commons/src/main/java/org/wikimedia/commons/Media.java

@@ -186,6 +186,7 @@ public String getDescription(String preferredLanguage) {
     }
 
     public Media(String filename) {
+        this();
         this.filename = filename;
     }