Slight tweak to gtasks api utilities, just in case somethings weird with dates

astrid/plugin-src/com/todoroo/astrid/gtasks/api/GtasksApiUtilities.java

@@ -10,7 +10,7 @@ import com.google.api.services.tasks.model.Task;
 public class GtasksApiUtilities {
 
     public static DateTime unixTimeToGtasksCompletionTime(long time) {
-        if (time == 0) return null;
+        if (time <= 0) return null;
         return new DateTime(new Date(time), TimeZone.getDefault());
     }
 
@@ -45,7 +45,7 @@ public class GtasksApiUtilities {
      * @return
      */
     public static DateTime unixTimeToGtasksDueDate(long time) {
-        if (time == 0) return null;
+        if (time <= 0) return null;
         Date date = new Date(time);
         date.setHours(0);
         date.setMinutes(0);