Adding hovercard event listeners for Users, Revisions, Conpherence and Commits

Summary:
Refs T1048

Adding Differential Hovercard EventListener

Adding People Hovercard EventListener

Adding basic Diffusion hovercard

Adding Conpherence Hovercard EventListener

Test Plan:
Used in a combo with working hovercards. So beautiful.

Also visited test page. Works alright.

awesometown

Reviewers: epriestley, chad, btrahan

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T1048

Differential Revision: https://secure.phabricator.com/D5576