create the ability to 'add' page permissions for users and groups

This is the ability to add page permissions for users and groups at the page level. This is different than issue CONF-3701 which talks about restricting permissions.

In many instances customers have offered a scenario where they have a somewhat restricted space but want to open up individual pages to a larger audience. For instance a technical team might want to open up a specification page to a larger audience, but don't want to open up everything and don't want to create a new space just for the spec. page.

This might be similar to a scaled down version of the process by which users and groups are given access to view and edit spaces....though this feature would be just for individual pages with the control most likely being offered on the page itself, as with the ability to restrict access.

This is a related issue, though not clearly defined: CONF-5682

There is also the case where a page needs to be open to viewing by anonymous users in a space which is otherwise inaccessible. If this issue were implemented, the UI should allow permitting anonymous access. (This was originally raised as CONF-10316.)