Revision 493916

Fix DIRSERVER-783. Ok, I admit this is a *huge* commit. 
Basically, here are the modification
- get rid of BasicAttribute(s), and replace them by Attribute(s)Impl
- renamed LockableAttribute(s)Impl to Attribute(s)Impl
- created a new ModificationItemImpl which extends ModificationItem for cloning purpose
- added a test for DIRSERVER-783
- fixed the way Attribute(s) are cloned
- fixed a lot of other errors in Attribute(s)Impl (mainly special cases)
- added more utility methods in AttributeUtils
- removed all the import javax.naming.directory.* all over the code (Please, do _not_ use * in imports !!!)