Added methods for 'simple' bind authentication in LdapTemplate (LdapOperations, SimpleLdapOperations and SimpleLdapTemplate as well).

Introduced new callback interface for use with certain authentication methods.
Added LdapEntryIdentification to wrap the full identification of an LDAP entry (absolute and relative DNs)
Added LdapEntryIdentificationContextMapper.

test-support/src/main/java/org/springframework/ldap/test/AttributeCheckContextMapper.java

@@ -49,7 +49,7 @@ public class AttributeCheckContextMapper implements ContextMapper {
             Assert.assertNull(adapter.getStringAttribute(absentAttributes[i]));
         }
 
-        return null;
+        return adapter;
     }
 
     public void setAbsentAttributes(String[] absentAttributes) {