Fix (?) an issue with CCs not being written into commit messages properly

Summary: Report from @zeeg, I think this is the root issue. Currently, if a project is CC'd we'll write "CC: projectname", but should write "CC: #projectname".

Test Plan: Verified that we now write "CC: #projectname".

Reviewers: btrahan, zeeg

Reviewed By: zeeg

CC: zeeg, aran

Differential Revision: https://secure.phabricator.com/D8296