Implicitly CC inline commenters in Pholio

Summary: Fixes T2722. Both the "comment" (default) and "inline comment" (needs to be specialized) actions should imply CC.

Test Plan: Made an inline on a mock, got implicitly cc'd.

Reviewers: chad

Reviewed By: chad

CC: aran

Maniphest Tasks: T2722

Differential Revision: https://secure.phabricator.com/D5312