R1:4dae3e7e1fbf

Improve some UI/language for Phame posts when viewer doesn't have CAN_INTERACT

Summary: Ref T13661. Fix up some UI and language so it's more clear that this is about disabling blog comments.

Test Plan: Viewed UIs, saw some more usable strings.

Maniphest Tasks: T13661

Differential Revision: https://secure.phabricator.com/D21755