Finding raised hands

[edemaine]

• [x] Indicate in Meetings Rooms tab of how many hands raised
• [x] Clicking on indicator brings to first/next hand
• [ ] "Hand down here" indicator at bottom, if there's one off-screen (and similarly on top)
• [ ] "Hand filtered out by search" indicator?
• [x] Drop shadow on raised hands
• [x] Sound when new hand raised