Pull out duplicated property definitions in the API into
register_standard_option/get_standard_option calls.
(All parameters, which are thus added to the API calls were optional).
Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
Die with a helpful error message instead of silently ignoring the user
when trying to delete a special role.
Also add a property to the API answer for possible later use by the
WebUI.
Reviewed-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
