Add support for tagging managed object definitions so that similar types of managed object can be grouped together. Tagging will enable us to automatically generate more user-friendly documentation and administration tools as a result of them being easier to navigate and search. For example, an administration CLI will be able to split the available set of sub-commands into categories, thus making it easier for administrators to find the sub-command that they need.

This change is implemented as follows:

* provide an extensible way in which tags can be defined: the XML root configuration definition element now supports an "adm:tag-definition" element, which can be used as follows:

  <adm:tag-definition name="logging">
    <adm:synopsis>Logging</adm:synopsis>
  </adm:tag-definition>

* provide a means for tagging managed object definitions with zero or more tags using an "adm:tag" element, which can be used as follows:

  <adm:tag name="logging"/>

* add support to the admin framework APIs for querying a managed object definition's tags

* define an initial set of tags and tag managed object definitions appropriately (this is just an initial guess and is likely to change):

  * logging
  * replication (incl. mmr)
  * database (incl. caching)
  * security (authn and authz)
  * identity (user account management, pwp, etc)
  * core (connection handlers, virtual attributes, etc)