Bug 857105 - Keep the item taped highlighted while the panel loads

- Replaces the hash/hashchange mechanism with a setter for currentPanel.
- Adds a 'panelready' event when the panel is displayed.
(cherry picked from commit eb6417144696335108a7fb1700ff2cfb57d6bf45)

Conflicts:
	apps/settings/js/settings.js
	apps/settings/style/lists.css
Merge pull request #10344 from Rik/stk-icc-lazy-loading-879773

Bug 879773 - STK panel can't be opened by async STK commands r=frsela(cherry picked from commit e3d191adfb54497524ddef31de2b6defc93bf4e7)
Bug 879773 - Fix linter tests shame=rik
(cherry picked from commit 81441427a3ee58410a70e79aec4a6fae40507c50)