Fixed Post.can_be_viewed_by to fix an issue introduced in 4cac7cf534e808efaadec5ff77bb961abfe0613c (some paths did not return, for instance if author is None and post is not public). Also put logic back to showing the post by default unless a security condition is not met. It's a bit less error prone (we code based on when the post should definitely not be shown).
Merge branch 'master' of github.com:efferifick/CMPUT404-project-socialdistribution