R1:20201364e55c

Add hover state to stackable list.

Summary: Adds a hover state, helpful for large stacked lists. Also applied dust to projects and config to go with the hover changes.

Test Plan: Config, Projects

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5223