Adjust ODM sample to demonstrate automatic mapping

[jzheaux]

Confusion like #459 can be alleviated in part by changing the ODM sample to not use @Attribute on fields whose field name matches the LDAP attribute name.

This reinforces the fact that no attribute annotation is needed for the field to be mapped to the entry. And it indirectly implies that @DnAttribute is not creating an entry mapping (since it is already there by default).