Merge pull request #1694 from mfietz/issue/1693-npe-dateutils-abbrev

Prevent NPE in DateUtils.abbrev()

core/src/main/java/de/danoeh/antennapod/core/util/DateUtils.java

@@ -145,6 +145,9 @@ public class DateUtils {
     }
 
     public static String formatAbbrev(final Context context, final Date date) {
+        if(date == null) {
+            return "";
+        }
         GregorianCalendar cal = new GregorianCalendar();
         cal.add(GregorianCalendar.YEAR, -1);
         // some padding, because no one really remembers what day of the month it is