Allow Space Admins to modify page restrictions

Problem

Currently Space Admins can be prevented from accessing the contents of a page, but they can use <base-url>/pages/listpermissionpages.action to reset the restrictions on a page in order to be able to view it. This can cause an issue if they don't remember what restrictions need to be put back on the page

Solution

Add the ability to not just remove restrictions, but also modify them at <base-url>/pages/listpermissionpages.action