Show shorter time in Conpherence, revisit spacing/colors

Summary: This adds a parameter for time only on Conpherence Transactions, although grepping around, Conpherence might be the only user of this View at this point. Since we have the date markers separately, we can use just the timestamp for a cleaner feel. Also updated a bit of the spacing and colors to match Conpherence Full. Ref T7531

Test Plan:
A lot of Photoshop, and different types of chats.

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T7531

Differential Revision: https://secure.phabricator.com/D12049