Test: use sinon.sandbox for easier test restore
Menu: Normalized mobile panel sub-headings to h3 elements
Merge pull request #4011 from pjackson28/fixmobilemenustructure

Menu: Normalized mobile panel sub-headings to h3 elements
Merge pull request #4007 from patheard/sandbox

Test: use sinon.sandbox for easier test restore
Multmedia: Various Fixes
- Removed the whitespace under the player
- Fixed display issues with the overlay button
- Fixed the overlay button not triggering a play
- Fixed aspect ratio for non 16:9 video
- Made Flash fallback and Youtube responsive