update getUserMedia article

[myakura]

things changed and made the article outdated but it looks like people still look at it.

• [x] update links
• [ ] expand the road to include Round 4 (from Navigator to MediaDevices.getUserMedia())
• [x] update example to use the new APIs
  • [x] navigator.mediaDevices.getUserMedia()
  • [x] MediaDevices.enumerateDevices()
  • [x] new constraints syntax
• [ ] add a note on Chrome and secure origin
• [ ] update demo embed in the article to use the new APIs
• [ ] advise to use adapter.js

[myakura]

and

• [ ] navigate to https

but it seems h5r doesn't support HTTPS :-(