Adding isManager/isViewer properties to content and discussion items

Added the following properties to content and discussion profiles:

 * isManager   - for when the user has explicit access to the object
 * isViewer (= isMember for discussions)
 * canManage
 * canShare

Discussions also have:
 * canView
 * canPost

Includes the follow-up for https://github.com/oaeproject/Hilary/pull/856
Good call on generalizing this, such a micro-optimization