Partial fix for issue 1426: improve support for required admin actions.
This change modifies the admin framework XML schema so that it is possible for all types of required admin action to have a description. For example, when there is no additional administrator action required when a property is modified, it is sometimes nice to indicate how the change will dynamically take effect.
In addition, it is now possible to query the specific type of admin action associated with a property and its synopsis via the admin framework APIs.