fixes the method addCurrencySymbol to return zero if

the parameter is null

FEA: ItEr76S04BugFixing

libreplan-webapp/src/main/java/org/libreplan/web/common/Util.java

@@ -661,6 +661,7 @@ public class Util {
      * {@link Configuration} object.
      */
     public static String addCurrencySymbol(BigDecimal value) {
+        value = (value == null ? BigDecimal.ZERO : value);
         DecimalFormat decimalFormat = (DecimalFormat) DecimalFormat
                 .getInstance();
         decimalFormat.applyPattern(getMoneyFormat());