CUNY Academic Commons

This'll take more review than we've currently got time for.

It turns out that the problem is actually quite specific: only sites with blog_public = 0 ("Discourage search engines...") are affected. All other privacy levels worked as expected, ie their content generated activity items. This is because of some odd hardcoded behavior in BuddyPress. I've proposed some changes there that should make this easier to work around in the future: https://buddypress.trac.wordpress.org/ticket/4831#comment:10

In the meantime, here's a fix for the Commons https://github.com/cuny-academic-commons/cac/commit/183aab16a2b14c774039631677078d7d832973b8. The one functionality decision I had to make was this: if group and site privacy levels differ (public site + private group, private site + public group), what should the privacy level of the activity item be? I opted to go conservative: if either the group or site is non-public, the activity item is non-public too. Note that "public" in the BP activity context means something odd: a "non-public" item can only be viewed on the associated item's activity thread, which is to say when you're looking at the group; for private groups, this means that only members can see it, since only members can view the group.

This needs testing on cdev to ensure that the various combinations of privacy make sense, and that the functionality works as promised.