Fixes #191: don't ignore the filter to exists method.

src/main/java/org/lsc/jndi/ScriptableJndiServices.java

@@ -117,7 +117,7 @@ public class ScriptableJndiServices extends ScriptableObject {
 
     protected List<String> _exists(final String dn, final String filter)
                           throws NamingException {
-        if (jndiServices.exists(dn)) {
+        if (jndiServices.exists(dn, filter)) {
             List<String> c = new ArrayList<String>();
             c.add(dn);