Minor tweaks to inline comments

Summary: Ref T7447, Ref T1460. Moves "done" state to left, and no longer is a button (simpler CSS). Also feels a little nicer. Clean up some spacing issue with Ghosties.

Test Plan:
Test new and old comments, as author and reviewer.

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Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: aik099, Korvin, epriestley

Maniphest Tasks: T1460, T7447

Differential Revision: https://secure.phabricator.com/D12641