[Bug #665] Fix bug

When allocating the hours in all a semester, only some minutes where
allocated each day. The error was that the day assigments that didn't
have at least one hour were discarded. Now only the ones with an
EffortDuration of zero are discarded.

FEA: ItEr61S05BugFixing

navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/ResourceAllocation.java

@@ -634,7 +634,7 @@ public abstract class ResourceAllocation<T extends DayAssignment> extends
         private List<T> onlyNonZeroHours(List<T> assignmentsCreated) {
             List<T> result = new ArrayList<T>();
             for (T each : assignmentsCreated) {
-                if (each.getHours() > 0) {
+                if (!each.getDuration().isZero()) {
                     result.add(each);
                 }
             }