Fix various app nav issues

Summary:

• Fix width, corresponding to wider sprites.
• Sprite the "Audit" icon.
• Mark the meta-application as device-ready.
• Fix some collapse/expand bugs with the draggable local navs.
• Add texture to local nav.
• Darken the application nav to make it more cohesive with the main nav. I think this is an improvement?

Test Plan: See screenshots.

Reviewers: chad, btrahan

Reviewed By: btrahan

CC: aran, netfoxcity

Maniphest Tasks: T1569

Differential Revision: https://secure.phabricator.com/D3338